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Andy did his undergraduate studies at the University of Lancaster and graduated with a first class honours in Chemistry in 1984. After graduating, he moved to Sussex University to undertake a PhD in Physical Organic Chemistry where he worked on developing an understanding of the intrinsic reactivity of aromatic compounds. He completed his PhD in September 1987 and was offered the opportunity to take up a research post at Huddersfield, working with Prof. Mike Page on the mechanisms by which enzymes catalyze reactions. Andy was appointed to the academic staff in 1989 and is currently a Reader in Organic Chemistry.
Throughout his time at Huddersfield, Andy has been a very active researcher; working in the areas of physical organic chemistry and analytical carbohydrate chemistry. He is currently the Deputy Director of the Biomolecular Sciences Research Centre and the Director of Research for the School of Applied Sciences. Andy currently works with a team of three postgraduate research students. In his current research he is exploring the mechanisms by which bacteria resist antibiotics and this includes studies of the interactions of bacterial enzymes with biologically active molecules and the analysis of the structure of the cell wall components of bacteria (using the latest analytical techniques-high field 2D-NMR and LC-MS-MS). Andy is also involved in emerging research in biofuels. A lot of Andys research is performed in collaboration with European partners.
Andys research expertise has been acknowledged through receipt of invitations: to speak at international conferences; to examine PhD students at a number of institutions and Andy is a referee for a number of international journals.
Bacteria have evolved that are able to survive in almost all environments. Frequently many different species of bacteria live together in a diverse community enveloped in slime. The slime acts both to protect them from changes in climatic conditions and helps them to adhere and survive in their immediate environment. Bacterial ecology is often complex and poorly understood; the conditions that support bacterial life can vary enormously within a few millimetres: bacteria at the surface will enjoy an aerobic environment whilst those below may well be faced with anaerobic conditions. The slime is frequently rich in hydrated polysaccharides and it is these polysaccharides that assist bacteria to inhabit such diverse environments. These polysaccharides are either attached to the cell surface (capsular polysaccharides) or are excreted into the local environment (exopolysaccharides EPS). The complex aggregates of bacterial colonies and their associated polysaccharides are referred to as biofilms; these biofilms are of great commercial significance and they have both negative and positive attributes. The generation of biofilms in food processing, especially in the Dairy Industry, results in spoilage of food. Biofilms provide a barrier for antibacterial agents and offer protection to bacteria from antibacterial agents. Recent research has suggested that difficulties encountered in removing Listeria from food preparation surfaces are related to their ability to excrete polysaccharides. In contrast, biofilms formed by non-pathogenic bacteria or âfriendly bacteriaâ are encouraged to enhance or protect dairy products: the lactic acid bacteria added to yoghurts generate polysaccharides which improve texture; biofilms formed on the surfaces of cheeses prevent spoilage by pathogenic strains.
In my research group we are interested in developing new techniques to characterise these polysaccharides.
Our existing projects have two main aims:
To isolate EPS, cultures are fermented and the fermentation is stopped by adding trichloroacetic acid (TCA). TCA precipitates DNA/RNA and proteins leaving carbohydrates in solution. Centrifugation provides a supernatant which is rich in small molecule carbohydrates; the polysaccharides are preferentially precipitated by adding an equal volume of chilled ethanol. The precipitated product is lightly contaminated with small molecule sugars and these are subsequently removed via exhaustive dialysis. This process is not optimal: the recovered EPS has limited solubility in aqueous solution and this suggests that a lot will be lost in the initial TCA precipitation (to date there have been no attempts to quantify these losses). The scientific literature contains numerous references to methods for improving EPS production, however, the reported success of many of these methods is frequently based on the yield of isolated material and they is rarely mention of the percentage recovery and, more importantly, the purity of the product obtained.
We are currently exploring several aspects of the isolation protocols:
At each stage of our isolation procedures we are using NMR spectroscopy to determine the purity of the product polysaccharide.
Current methods for the Characterisation of EPSs - before a polysaccharide can be considered to be fully characterised it is necessary to determine information about the molecular mass of the material, to identify the composition and absolute configuration of the monomers and, finally, to determine the linkage pattern of the monomers.
Historically, retention times determined by size exclusion chromatography and refractive-index detection have been used to determine molecular mass. However, the majority of EPS samples have very large molecular masses and elute close to the exclusion limits of the available stationary phases and very much in advance of the highest molecular mass standards used to calibrate the columns. Combination detectors using light scattering for measurement of molecular mass provide a more accurate average molecular mass and this technique is used at Huddersfield (SEC-MALLS).
A number of different methods are available for determining the monomer composition of EPS samples. Methanolysis and per-trimethylsilylation provides samples that can be analysed by GC. A simpler method, requiring acid hydrolysis followed by monomer detection using high pressure anion exchange chromatography with pulsed ampometric detection, has recently been introduced. Absolute configurations of monomers are determined by preparation of their per-trimethylsilyl (-)butyl glycosides. All of these techniques are available in our laboratories and a combination of these different techniques is chosen depending on the nature of the polysaccharide.
The linkage pattern of the monomers is determined using a combination of "methylation" analysis and NMR spectroscopy. Both techniques are well established but require significant quantities of material to be available. At Huddersfield 1D- 1H and 13C spectra are recorded for solutions of EPS samples in deuterium oxide and spectra are recorded at temperatures of 70°C or above. Homonuclear 2D-spectra are used to assign protons resonances to individual rings (COSY and TOCSY) and heteronuclear 2D spectra, 13C-1H, are used to assign carbons (HMQC, HMBC) and to obtain linkage information (HMBC). Further information about linkage, using non-scalar coupling, is available from ROESY spectra.
Unfortunately, these techniques require a lot of time to complete, a lot of expensive instrumentation and expert analysts. They also only work if a significant amount of polysaccharide is available.
Developing the characterisation procedure: Development of a rapid method for hexose analysis using liquid chromatography-mass spectrometry (an alternative to monomer analysis).
Current methods for monomer analysis are far from ideal (see discussion above). Techniques for the detection and selective identification of very small amounts of hexoses are urgently required if the field of glycobiology is to advance rapidly. At Huddersfield we are looking at the use of selective derivatisation and the use of MS of derivatised sugars to provide a rapid and sensitive analytical method for monomer analysis.
Development of method for combined sequence and linkage analysis using liquid chromatography-mass spectrometry.
It is not possible to do sequence analysis on small quantities of material.A quick and rapid method for determining the linkage pattern of the polysaccharide would be to perform tandem mass spectrometry on the native sample. In tandem mass spectrometry the native material is fragmented into various sized pieces and the original structure is determined from the different masses of the fragments. This technique could provide us with the types of linkage present but, because different hexoses have exactly the same mass, it can't presently be used for sequence identification.
In our current work we are exploring methods for derivatising the native polysaccharide to assist with linkage analysis. In one project, the native polysaccharide is being subjected to oxidation reactions. In the literature there are several reports of oxidation reactions being used to modify intact polysaccharides. We have used two methods: TEMPO oxidation of primary alcohols and periodate oxidation of vicinal alcohols. Under controlled conditions TEMPO and periodate oxidation reactions are regio and stereoselective and this will allow us to identify several linkages. Once oxidised the derivatised oligosaccharides can be sequenced using tandem mass spectrometry using electrospray ionisation.
For indicative references see separate publication list
Bacteria have evolved to evade the action of penicillin and cephalosporin antibiotics; whilst there are numerous molecular mechanisms for resistance the production of beta-lactamase enzymes is the most prominent. Beta-lactamases efficiently catalyse the hydrolysis of the amide bond of beta-lactam antibiotics to generate inactive beta-amino acids:
To date, over 400 different beta-lactamases have been identified with individual enzymes having either a broad specificity (they hydrolyse a large range of beta-lactam antibiotics) or a narrow specificity (they hydrolyse specific antibiotics). These enzymes have been classified into one of four different groups depending on their substrate profiles and their mode of action: classes A, B, C and D. Classes A, C and D are serine proteases and they have an active site serine residue which is temporarily acylated by the beta-lactam during the hydrolysis reaction.
In contrast, class B beta-lactamases are metallo-enzymes that utilise a metal bound water to hydrolyse the amide linkage without the involvement of any covalently linked intermediates:
At Huddersfield we have prepared a number of small molecules which are able to act as inhibitors of the serine beta-lactamases and these are substituted beta-sultams (1,2-thiazetidine-1,1-dioxides). Beta-sultams are structurally very similar to beta-lactam antibiotics: the sulphonyl group simply substituting for the carbonyl; they do however have enhanced chemical reactivity. In our labs we have prepared a series of lactams (1), sultams (2) and oxosultams (3) and are currently investigating their interaction with bacterial enzymes:
Studying the interaction of beta-sultams (2) with class C beta-lactamase of Enterobacter clocae.
Our previous studies have shown that N-benzoyl beta-sultam (2, R=COPh) inhibits class C beta-lactamases, incubation of the enzyme with the inhibitor results in a rapid loss of the ability of the enzyme to catalyse the hydrolysis of beta-lactam antibiotics. We have been able to demonstrate that the mode of inhibition is similar to the mode by which the enzyme catalyses the hydrolysis of its substrate: the pH dependence of the inhibition is the same as that of the catalysis reaction and the rate of inhibition can be slowed by adding competing substrates. These latter two factors suggest that the beta-sultams are acting at the active site of the enzyme. The anticipated mechanism would involve the attack of the serine hydroxyl at the sulphonyl centre to form a sulphonylated enzyme:
The inhibition process was monitored using electrospray mass spectrometry: covalent attachment of the inhibitor (mass 211) to the enzyme (mass 39184) would provide an adduct of increased mass (39295). When the experiment was performed the expected mass increase was initially observed but the resulting species was not stable: a new adduct with a mass equivalent to that of the enzyme minus eighteen was observed. Treatment of the enzyme with large amounts of the inhibitor also showed that it was possible to get a further product and it is not clear what is happening. Current investigations are directed at determining the mechanism of this reaction. We are studying the inhibition of the serine enzyme using mass spectrometry. In this investigation it is our intention to sequence both the enzyme and inhibited products, generated by reaction with sultams and oxosultams, using the tools of proteomics. Tryptic digests of the enzyme (control system) and inhibited-enzyme will give fragments. Knowing the cleavage pattern of trypsin and the amino acid sequence of the enzyme will allow us to identify fragments including those of the active site. In the class C beta-lactamases the active site has previously been identified as serine 64. If covalent attachment is at the active site then we would expect any mass differences to be present in the active site fragments. Using tandem mass spectrometry it will be possible to isolate these fragments and then to do collision induced fragmentation to determine their structure. Once the structures of the modified adducts are known it should be possible to provide a more comprehensive picture for the inhibition process.
The oxo-sultams are unique compounds in that they retain the lactam amide as well as having the sulphonyl centre. Our previous studies have shown that the N-benzyl-oxo-sultams also irreversibly inhibit the class C beta-lactamases. When the inhibition reaction was studied using electrospray mass spectrometry a new adduct was formed having a mass equivalent to that of the enzyme plus the inhibitor and, with the oxo-sultams, the enzyme-inhibitor adduct was stable.
The latter result suggested that either the sulphonylated enzyme was now stable or that the inhibitor was acylating the enzyme rather than sulphonylating the enzyme:
It is not clear which of these two processes is occurring. One way of differentiating between the two is to monitor the reaction of the enzyme-inhibitor complex in the presence of external nucleophiles. When serine beta-lactamases are acylated by beta-lactams the initial acylated enzyme (4) is slowly hydrolysed to regenerate the enzyme and the ring opened inhibitor. If the inhibited enzyme is treated with an external nucleophile (Nu) then we would expect to form a carboxyl derivative. As part of the programme of work the reaction of oxo-sultams with the class C beta-lactamase from Enterobacter cloacae P99 will be monitored by electrospray mass spectrometry to study the formation of the inhibited enzyme. Once the inhibited enzyme has been produced excess inhibitor will be removed by treatment with base and subsequent recovery of the inhibited enzyme will be performed by ultra-filtration. The reaction of the ultra-filtrated enzyme with excess external nucleophile will then be monitored using electrospray mass spectrometry to detect nucleophilic adducts.
For indicative references see separate publication list
Almond, M., Shaw, P., Humphreys, P., Chadha, M., Niemelä, K. and Laws, A. (2012) ‘Behavior of xyloisosaccharinic acid and xyloisosaccharino-1,4-lactone in aqueous solutions at varying pHs’ Carbohydrate Research , 363, pp. 51-57. ISSN 00086215
Ponomarov, O., Laws, A. and Hanusek, J. (2012) ‘1,2,4-Dithiazole-5-ones and 5-thiones as Efficient Sulfurizing Agents of Phosphorus (III) Compounds A Kinetic Comparative Study’ Organic and Biomolecular Chemistry . ISSN 1477-0539
Leivers, S., Hidalgo-Cantabrana, C., Robinson, G., Margolles, A., Ruas-Madiedo, P. and Laws, A. (2011) ‘Structure of the high molecular weight exopolysaccharide produced by Bifidobacterium animalis subsp. lactis IPLA-R1 and sequence analysis of its putative eps cluster’ Carbohydrate Research , 346 (17), pp. 2710-2717. ISSN 00086215
Humphreys, P., Laws, A. and Dawson, J. (2010) A Review of Cellulose Degradation and the Fate of Degradation Products Under Repository Conditions Cumbria, UK: Nuclear Decommissioning Authority (NDA)
Laws, A., Leivers, S., Chacon-Romero, M. and Chadha, M. (2009) ‘Variation in the molecular mass of exopolysaccharides during the time course of extended fermentations of skimmed milk by lactic acid bacteria’ International Dairy Journal , 19 (12), pp. 768-771. ISSN 0958-6946
Russell, M., Laws, A., Atherton, J. and Page, M. (2009) ‘The kinetics and mechanism of the acid-catalysed detritylation of nucleotides in non-aqueous solution’ Organic and Biomolecular Chemistry , 7 (1), pp. 52-57. ISSN 1477-0539
Russell, M., Laws, A., Atherton, J. and Page, M. (2008) ‘The mechanism of the phosphoramidite synthesis of polynucleotides’ Organic and Biomolecular Chemistry , 6 (18), pp. 3270-3275. ISSN 1477-0539
Laws, A., Chadha, M., Chacon-Romero, M., Marshall, V. and Maqsood, M. (2008) ‘Determination of the structure and molecular weights of the exopolysaccharide produced by Lactobacillus acidophilus 5e2 when grown on different carbon feeds’ Carbohydrate Research , 343 (2), pp. 301-307. ISSN 00086215
Clayton, H., Harding, L., Irvine, J., Jeffery, J., Riis-Johannessen, T., Laws, A., Rice, C. and Whitehead, M. (2008) ‘Metal-specific allosteric activation and deactivation of a diamine’ Chemical Communications (1), p. 108. ISSN 1364-548X
Hanusek, J., Russell, M., Laws, A. and Page, M. (2007) ‘Evidence for the formation of isothiocyanate during sulphurisation of triphenyl phosphines using xanthane hydride ’ Tetrahedron Letters , 48 (3), pp. 417-419. ISSN 0040-4039
Hanusek, J., Russell, M., Laws, A., Jansa, P., Atherton, J., Fettes, K. and Page, M. (2007) ‘Mechanism of the sulphurisation of phosphines and phosphites using 3-amino-1,2,4-dithiazole-5-thione (Xanthane Hydride) ’ Organic and Biomolecular Chemistry , 5 (3), pp. 478-484. ISSN 1477-0539
Llinas, A., Ahmed, N., Cordaro, M., Laws, A., Frere, J., Delmarcelle, M., Silvaggi, N., Kelly, J. and Page, M. (2005) ‘The inactivation of bacterial DD-peptidase by ?-sultams ’ Biochemistry , 44 (21), pp. 7738-7746. ISSN 1520-4995
Badarau, A., Llinas, A., Laws, A., Damblon, C. and Page, M. (2005) ‘Inhibitors of metallo-?-lactamase generated from ?-lactam antibiotics ’ Biochemistry , 44 (24), pp. 8578-8589. ISSN 1520-4995
Harding, L., Marshall, V., Hernandez, Y., Gu, Y., Maqsood, M., McLay, N. and Laws, A. (2005) ‘Structural characterisation of the highly branched exopolysaccharide produced by Lactobacillus delbrueckii subsp. Bulgaricus NCFB2074’ Carbohydrate Research , 340 (6), pp. 1107-1111. ISSN 0008-6215
Tsang, W., Ahmed, N., Hinchliffe, P., Wood, J., Harding, L., Laws, A. and Page, M. (2005) ‘Different transition-state structures for the reactions of ?-lactams and analogous ?-sultams with serine ?-lactamases ’ Journal of the American Chemical Society , 127 (49), pp. 17556-17564. ISSN 1520-5126
Tsang, W., Ahmed, N., Harding, L., Hemming, K., Laws, A. and Page, M. (2005) ‘Acylation versus sulfonylation in the inhibition of elastase by 3-oxo-beta-sultams ’ Journal of the American Chemical Society , 127 (25), pp. 8946-8947. ISSN 1520-5126
Vaningelgem, F., Van der Meulen, R., Zamfir, M., Adriany, T., Laws, A. and De Vuyst, L. (2004) ‘Streptococcus thermophilus ST 111 produces a stable high-molecular-mass exopolysaccharide in milk-based medium’ International Dairy Journal , 14 (10), pp. 857-864. ISSN 09586946
Page, M., Hinchliffe, P., Wood, J., Harding, L. and Laws, A. (2003) ‘Novel mechanism of inhibiting b-lactamases by sulfonylation using b-sultams ’ Bioorganic & Medicinal Chemistry Letters , 13 (24), pp. 4489-4492. ISSN 0960-894X
Harding, L., Marshall, V., Elvin, M., Gu, Y. and Laws, A. (2003) ‘Structural characterisation of a perdeuteriomethylated exoploysaccharide by NMR spectroscopy: characterisation of the novel exopolysaccharide produced by Lactobacillus delbrueckii subsp. Bulgaricus EU23’ Carbohydrate Research , 338 (1), pp. 61-67. ISSN 0008-6215
Wood, J., Hinchliffe, P., Laws, A. and Page, M. (2002) ‘Reactivity and the mechanism of reactions of ?-sultams with Nucleophiles’ Journal of the Chemical Society Perkins Transactions 2 , pp. 938-946. ISSN 1364-5471
Laws, A. and Marshall, V. (2001) ‘The relevance of exopolysaccharides to the rheological properties in milk fermented with ropy strains of lactic acid bacteria’ International Dairy Journal , 11 (9), pp. 709-721. ISSN 0958-6946
Degeest, B., Vaningelgem, F., Laws, A. and De Vuyst, L. (2001) ‘UDP-N-Acetylglucosamine 4-Epimerase Activity Indicates the Presence of N-Acetylgalactosamine in Exopolysaccharides of Streptococcus thermophilus Strains’ Applied and Environmental Microbiology , 67 (9), pp. 3976-3984. ISSN 0099-2240
Laws, A., Gu, Y. and Marshall, V. (2001) ‘Biosynthesis, characterisation, and design of bacterial exopolysaccharides from lactic acid bacteria’ Biotechnology Advances , 19 (8), pp. 597-625. ISSN 0734-9750
Marshall, V., Laws, A., Gu, Y., Levander, F., Radstrom, P., De Vuyst, L., Degeest, B., Vaningelgem, F., Dunn, H. and Elvin, M. (2001) ‘Exopolysaccharide-producing strains of thermophilic lactic acid bacteria cluster into groups according to their EPS structure’ Letters in Applied Microbiology , 32 (6), pp. 433-435. ISSN 02668254
Laws, A. and Marshall, V. (2001) ‘The relevance of exopolysaccharides to the rheological properties in milk fermented with ropy strains of lactic acid bacteria’ International Dairy Journal , 11, pp. 709-721. ISSN 0958-6946
Slater, M., Laws, A. and Page, M. (2001) ‘The relative catalytic efficiency of ?-lactamase catalysed acyl and phosphyl transfer ’ Bioorganic Chemistry , 29, pp. 77-95. ISSN 0045-2068
Marshal, V., Dunn, H., Elvin, M., McLay, N., Gu, Y. and Laws, A. (2001) ‘Structural characterisation of the exopolysaccharide produced by Streptococcus Thermophilis EU20’ Carbohydrate Research , 331 (4), pp. 413-422. ISSN 0008-6215
Bounaga, S., Galleni, M., Laws, A. and Page, M. (2001) ‘Cysteinyl peptide Inhibitors of Bacillus cereus Zinc ?-Lactamase’ Bioorganic & Medicinal Chemistry Letters , 9 (2), pp. 503-507. ISSN 0960-894X
Baxter, N., Rigoreau, L., Laws, A. and Page, M. (2000) ‘Reactivity and Mechanism in the Hydrolysis of ?-Sultams’ Journal of the American Chemical Society , 122 (14), pp. 3375-3380. ISSN 1520-5126
Page, M. and Laws, A. (2000) ‘The Chemical Reactivity of ?-Lactams, ?-Sultams and ?-Phospholactams’ Tetrahedron , 56 (31), pp. 5631-5637. ISSN 0040-4020
Page, M. and Laws, A. (1998) ‘The mechanism of catalysis and the inhibition of ?-lactamases’ Chemical Communications (16), pp. 1609-1617. ISSN 1359-7345
Bounaga, S., Laws, A., Galleni, M. and Page, M. (1998) ‘The mechanism of catalysis and the inhibition of the Bacillus cereus zinc-dependent b-lactamase ’ Biochemical Journal , 331 (3), pp. 703-711. ISSN 0264-6021
Baxter, N., Laws, A., Rigoreau, L. and Page, M. (1996) ‘The hydrolytic reactivity of B-sultams’ Journal of the Chemical Society, Perkin Transactions 2 (11), p. 2245. ISSN 1472-779X
Laws, A. and Page, M. (1996) ‘The chemistry and structure-activity relationships of C3-quaternary ammonium cephem antibiotics’ Journal of Chemotherapy , 8, pp. 7-22. ISSN 1120-009X
Page, M., Laws, A., Slater, M. and Stone, J. (1995) ‘Reactivity of ?-lactams and phosphonamidates and reactions with ?-lactamase’ Pure and Applied Chemistry , 67 (5), pp. 711-717. ISSN 0033-4545
Layland, N., Laws, A., Vilanova, B. and Page, M. (1995) ‘Penicillin 3-aldehyde is a good substrate and not an inhibitor of ?-lactamases A and C’ Journal of the Chemical Society, Perkin Transactions 2 (5), pp. 869-870. ISSN 1472-779X
Barton, P., Laws, A. and Page, M. (1994) ‘Structure-activity relationships in the esterase-catalysed hydrolysis and transesterification of esters and lactones’ Journal of the Chemical Society, Perkin Transactions 2 (9), pp. 2021-2029. ISSN 1472-779X
Laws, A., Stone, J. and Page, M. (1994) ‘Large rate enhancement for the hydrolysis of a four-membered ring phosphonamidate’ Chemical Communications (10), pp. 1223-1224. ISSN 1359-7345
Laws, A., Page, M. and Slater, M. (1993) ‘The mechanism of reactions catalysed by the serine ?-lactamases’ Bioorganic & Medicinal Chemistry Letters , 3 (11), pp. 2317-2322. ISSN 0960-894X
Laws, A., Layland, N., Proctor, D. and Page, M. (1993) ‘The roles of the carboxy group in ?-lactam antibiotics and lysine 234 in ?-lactamase I’ Journal of the Chemical Society, Perkin Transactions 2 (1), pp. 17-21. ISSN 1472-779X
Page, M. and Laws, A. (1990) ‘Molecular recognition in beta lactamases’. In: Molecular mechanisms in bioorganic processes. : Royal Society of Chemistry. pp. 319-330. ISBN 9780851869469
Laws, A. and Page, M. (1989) ‘The effect of the carboxy group on the chemical and ?-lactamase reactivity of ?-lactam antibiotics’ Journal of the Chemical Society, Perkin Transactions 2 (10), pp. 1577-1581. ISSN 1472-779X
Complex carbohydrates are routinely used either directly or bonded to other classes of biological macromolecules to impart function. In my research team we are developing new methods for the rapid analysis of complex carbohydrates with a view to determining the functional role played by carbohydrates in nature. Postgraduate students working in this area will be exposed to the application of high field NMR and tandem LC/MS/MS to the characterisation of carbohydrate based materials.
Exopolysaacharides (EPS) excreted by bacteria allow them to inhabit a vast variety of environments. Little is known about the physical properties of exoploysaccharides and how they contribute to their ability to adhere to surfaces. Research at Huddersfield is directed at producing, isolating, characterising and comparing the physical properties of EPSs. We employ microbiologists to study the generation of EPSs by bacteria and are interested in looking at a wide range of different organisms to determine appropriate physiological conditions that promote EPS synthesis and isolation.
The acid catalysed decomposition of polysaccharides generates small organic molecules that have potential for use as biofuels. At Huddersfield we are interested in looking at the development of a range of ionic liquids containing Lewis acid catalysts that can be used for the degradation of plant based polysaccharides. Postgraduate students working in this area will be exposed to analytical techniques required for the determination of products derived from both the acid catalysed and thermal decomposition of complex carbohydrates.
At Huddersfield we have a strong tradition of undertaking research directed at determining the mechanisms of organic reactions. Much of the work has focused on the study of small ring systems and studying their interaction with nucleophiles. The small ring lactams and sultams generated by our group have demonstrated considerable biological activity; they inhibit bacterial serine proteases and esterases.
We are currently looking at the interaction of cysteine proteases with small ring systems containing electrophilic groups. Postgraduates working in this area undertake classical physical organic studies; students are employed to develop structure activity relationships and to determine reaction mechanisms.
Increasingly bacteria are developing resistance to beta-lactam antibiotics. One of the major defence mechanisms used by bacteria to evade the action of penicillins and cephalosporins is to generate enzymes that can catalyse the hydrolysis of these substrates. Opportunities are available for students to study the mechanisms by which bacterial enzymes catalyse destruction of antibacterials. Projects involve students both in the preparation of novel inhibitors of beta-lactamases and studies of their mode of reaction.