J. Coggins

发表

Evidence for the shikimate pathway in apicomplexan parasites

D. Chakrabarti, F. Roberts, C. Roberts, 1998, Nature.

Structures of Shikimate Dehydrogenase AroE and Its Paralog YdiB

Allan Matte, Miroslaw Cygler, Adrian J. Lapthorn, 2003, Journal of Biological Chemistry.

Shikimate dehydrogenase from Escherichia coli.

J. Coggins, S. Chaudhuri, I. Anton, 1987, Methods in enzymology.

[40] Shikimate dehydrogenase from escherichia coli

J. Coggins, S. Chaudhuri, I. Anton, 1987 .

Over-expression of the yeast multifunctional arom protein.

J. Coggins, L. Graham, F. M. Gillies, 1993, Biochimica et biophysica acta.

The complete amino acid sequence of 3-dehydroquinate synthase of Escherichia coli K12.

J. Coggins, G. Millar, 1986, FEBS letters.

The serC-aro A operon of Escherichia coli. A mixed function operon encoding enzymes from two different amino acid biosynthetic pathways.

J. Coggins, K. Duncan, 1986, The Biochemical journal.

Propionyl-CoA carboxylase from Streptomyces coelicolor A3(2): cloning of the gene encoding the biotin-containing subunit.

J. Coggins, I. Hunter, H. G. Nimmo, 1996, Microbiology.

A complete shikimate pathway in Toxoplasma gondii: an ancient eukaryotic innovation.

C W Roberts, T A Richards, C. Roberts, 2004, International journal for parasitology.

The anatomy of a multifunctional enzyme.

J. Coggins, D. Mousdale, I. Anton, 1987, Biochemical Society transactions.

Specificity of substrate recognition by type II dehydroquinases as revealed by binding of polyanions1

N. C. Price, J. Coggins, D. Robinson, 2002, FEBS letters.

Mechanistic studies on type I and type II dehydroquinase with (6R)- and (6S)-6-fluoro-3-dehydroquinic acids.

J. Coggins, A. Hawkins, E. Parker, 2000, Bioorganic & medicinal chemistry letters.

The folding and assembly of the dodecameric type II dehydroquinases.

N. C. Price, T. Krell, J. Coggins, 1999, The Biochemical journal.

The study of cell-death proteins in the outer mitochondrial membrane by chemical cross-linking.

J. Coggins, H. Jacobs, S. Ali, 1997, The Biochemical journal.

Structure of bovine cytochrome oxidase

J. Coggins, M. Wikström, M. Saraste, 1980, FEBS letters.

Subcellular localization of the common shikimate-pathway enzymes in Pisum sativum L.

J. Coggins, D. Mousdale, 1985, Planta.

Synthesis of 3-deoxy-3,3-difluoroshikimic acid and its 4-epimer from quinic acid

Gurdial Singh, J. Coggins, Shende Jiang, 1999 .

Multidomain proteins : structure and evolution

J. Coggins, D. Hardie, 1986 .

Rapid chromatographic purification of glyphosate-sensitive 5-enolpyruvylshikimate 3-phosphate synthase from higher plant chloroplasts.

J. Coggins, D. Mousdale, 1986, Journal of chromatography.

Resonance Raman spectroscopic studies on intact cytochrome P450 BM3.

J. Coggins, A. Munro, J. Lindsay, 1994, Biochemical Society transactions.

Amino Acid Synthesis

J. Coggins, D. Mousdale, 1991 .

Methods for obtaining peptide maps of proteins on a subnanomole scale.

J. Coggins, R. Perham, D. L. Bates, 1975, Analytical biochemistry.

Purification, crystallization and preliminary X-ray crystallographic analysis of ATP-phosphoribosyltransferase from Escherichia coli.

J. Coggins, A. Lapthorn, B. Lohkamp, 2000, Acta crystallographica. Section D, Biological crystallography.

Crystallization and preliminary X-ray analysis of shikimate dehydrogenase from Escherichia coli.

J. Coggins, J. Maclean, A. Lapthorn, 2000, Acta crystallographica. Section D, Biological crystallography.

Affinity labelling of proteinases with tryptic specificity by peptides with C-terminal lysine chloromethyl ketone.

J. Coggins, E. Shaw, W. Kray, 1974, The Biochemical journal.

Affinity labelling of E. coli dehydroquinase

J. Coggins, C. Abell, T. Bugg, 1988 .

Specificity of E. Coli shikimate dehydrogenase towards analogues of 3-dehydroshikimic acid

J. Coggins, C. Abell, T. Bugg, 1988 .

Chorismate synthase from Staphylococcus aureus.

J. Coggins, T. Foster, M. Horsburgh, 1996, Microbiology.

The use of mass spectrometry to examine the formation and hydrolysis of the phosphorylated form of phosphoglycerate mutase

N. C. Price, T. Krell, J. Coggins, 1995, FEBS letters.

Identification of 4-amino-4-deoxychorismate synthase as the molecular target for the antimicrobial action of (6s)-6-fluoroshikimate.

J. Coggins, E. Parker, Elaine Stephens, 2004, Journal of the American Chemical Society.

Escherichia coli Chorismate Synthase Catalyzes the Conversion of (6S)-6-Fluoro-5-enolpyruvylshikimate-3-phosphate to 6-Fluorochorismate

S. Balasubramanian, J. Coggins, S. Bornemann, 1995, The Journal of Biological Chemistry.

Escherichia coli chorismate synthase: a deuterium kinetic-isotope effect under single-turnover and steady-state conditions shows that a flavin intermediate forms before the C-(6proR)-H bond is cleaved.

S. Balasubramanian, J. Coggins, S. Bornemann, 1995, The Biochemical journal.

Purification and properties of 5-enolpyruvylshikimate 3-phosphate synthase from seedlings of Pisum sativum L.

J. Coggins, D. Mousdale, 2004, Planta.

Purification and properties of a glyphosate-tolerant 5-enolpyruvylshikimate 3-phosphate synthase from the cyanobacterium Anabaena variabilis

J. Coggins, D. Mousdale, N. W. Kerby, 1992, Planta.

A catalase from Streptomyces coelicolor A3(2).

J. Coggins, I. Hunter, H. G. Nimmo, 1995, Microbiology.

The efficiency of folding of some proteins is increased by controlled rates of translation in vivo. A hypothesis.

A. Brown, I. Purvis, J. Coggins, 1987, Journal of molecular biology.

Functional domains involved in aromatic amino acid biosynthesis.

J. Coggins, D. Mousdale, D. Smith, 1985, Biochemical Society transactions.

A study of the quaternary structure of Escherichia coli RNA polymerase using bis(imido esters).

J. Coggins, A. Malcolm, J. Lumsden, 1977, Biochemistry.

Use of dimethyl suberimidate and novel periodate-cleavable bis(imido esters) to study the quaternary structure of the pyruvate dehydrogenase multienzyme complex of Escherichia coli.

J. Coggins, R. Perham, E. Hooper, 1976, Biochemistry.

Plant protein phosphatases. Subcellular distribution, detection of protein phosphatase 2C and identification of protein phosphatase 2A as the major quinate dehydrogenase phosphatase.

P. Cohen, J. Coggins, C. MacKintosh, 1991, The Biochemical journal.

Detection and subcellular localization of a higher plant chorismate synthase

J. Coggins, D. Mousdale, 1986 .

The subunit structure of the arom multienzyme complex of Neurospora crassa. A possible pentafunctional polypeptide chain.

J. Coggins, J. Lumsden, 1977, The Biochemical journal.

[41] 3-Dehydroquinate dehydratase from escherichia coli

J. Coggins, S. Chaudhuri, K. Duncan, 1987 .

3-Dehydroquinate dehydratase from Escherichia coli.

J. Coggins, S. Chaudhuri, K. Duncan, 1987, Methods in enzymology.

The arom multifunctional enzyme from Neurospora crassa.

J. Coggins, S. Chaudhuri, D. Smith, 1987, Methods in enzymology.

3-Phosphoshikimate 1-carboxyvinyltransferase from Escherichia coli.

J. Coggins, A. Lewendon, 1987, Methods in enzymology.

Purification and characterization of 3-dehydroquinase from Escherichia coli.

J. Coggins, S. Chaudhuri, J. Lambert, 1986, The Biochemical journal.

Escherichia coli dihydrodipicolinate synthase: characterization of the imine intermediate and the product of bromopyruvate treatment by electrospray mass spectrometry.

J. Coggins, C. Abell, S. Connell, 1995, The Biochemical journal.

The reaction of GroEL (cpn 60) with the ATP analogue 2',3' dialdehyde ATP

N. C. Price, J. Coggins, G. Thomson, 1993, FEBS letters.

Kinetics of 5‐enolpyruvylshikimate‐3‐phosphate synthase inhibition by glyphosate

J. Coggins, M. Boocock, 1983, FEBS letters.

Phosphoenolpyruvate carboxylase from Streptomyces coelicolor A3(2): purification of the enzyme, cloning of the ppc gene and over-expression of the protein in a streptomycete.

J. Coggins, I. Hunter, H. G. Nimmo, 1993, The Biochemical journal.

Phosphoenolpyruvate carboxylase from the crassulacean plant Bryophyllum fedtschenkoi Hamet et Perrier. Purification, molecular and kinetic properties.

J. Coggins, C. A. Fewson, A. Malcolm, 1978, The Biochemical journal.

The structure and mechanism of the type II dehydroquinase from Streptomyces coelicolor.

Chris Abell, T. Krell, J. Coggins, 2002, Structure.

Re-evaluating the Role of His-143 in the Mechanism of Type I Dehydroquinase from Escherichia coli Using Two-dimensional1H,13C NMR*

J. Coggins, R. Boetzel, G. Moore, 1998, The Journal of Biological Chemistry.

The unfolding and attempted refolding of the bacterial chaperone protein groEL (cpn60).

N. C. Price, J. Coggins, S. Wood, 1993, Biochimica et biophysica acta.

A comparison of the enzymological and biophysical properties of two distinct classes of dehydroquinase enzymes.

N. C. Price, J. Coggins, A. Hawkins, 1992, The Biochemical journal.

Synthesis of N-Methylamino Acid Derivatives from Amino Acid Derivatives using Sodium Hydride/Methyl Iodide

J. Coggins, N. Benoiton, 1971 .

Studies on human pregnancy-associated plasma protein A. Purification by affinity chromatography and structural comparisons with alpha 2-macroglobulin.

J. Coggins, R. Sutcliffe, J. Hunter, 1980, The Biochemical journal.

Reaction of (6R)-6-fluoroEPSP with recombinant Escherichia coli chorismate synthase generates a stable flavin mononucleotide semiquinone radical

S. Balasubramanian, J. Coggins, T. Hawkes, 1992 .

The overexpression and complete amino acid sequence of Escherichia coli 3-dehydroquinase.

J. Coggins, K. Duncan, S. Chaudhuri, 1986, The Biochemical journal.

Observation of a secondary tritium isotope effect in the chorismate synthase reaction.

S. Balasubramanian, J. Coggins, C. Abell, 1995, Biochemistry.

Probing electron transfer in flavocytochrome P-450 BM3 and its component domains.

J. Coggins, A. Munro, S. Daff, 1996, European journal of biochemistry.

NADPH oxidase activity of cytochrome P-450 BM3 and its constituent reductase domain.

N. C. Price, J. Coggins, A. Munro, 1995, Biochimica et biophysica acta.

Determination of N-methylamino acids and their optical purity with an amino acid analyzer.

J. Coggins, N. Benoiton, 1970, Journal of chromatography.

Comparison of the substrate specificity of type I and type II dehydroquinases with 5-deoxy- and 4,5-dideoxy-dehydroquinic acid

J. Coggins, A. Hawkins, C. Abell, 1996 .

The use of electrospray mass spectrometry to identify an essential arginine residue in type II dehydroquinases

T. Krell, J. Coggins, A. Pitt, 1995, FEBS letters.

Crystallization of a type II dehydroquinase from Mycobacterium tuberculosis.

I. Charles, N. Isaacs, J. Coggins, 1994, Journal of Molecular Biology.

Purification and characterization of a dual function 3-dehydroquinate dehydratase from Amycolatopsis methanolica.

L. Dijkhuizen, J. Coggins, G. Euverink, 1992, Journal of General Microbiology.

Observation of an imine intermediate on dehydroquinase by electrospray mass spectrometry

J. Coggins, C. Kleanthous, C. Abell, 1991 .

The purification and characterization of 3-dehydroquinase from Streptomyces coelicolor.

J. Coggins, I. Hunter, H. G. Nimmo, 1990, The Biochemical journal.

(1R,4S,5R)-3-Fluoro-1,4,5-trihydroxy-2-cyclohexene-1-carboxylic acid: the fluoro analogue of the enolate intermediate in the reaction catalyzed by type II dehydroquinases.

J. Coggins, C. Abell, A. Lapthorn, 2004, Organic & biomolecular chemistry.

ENZYMATIC SYNTHESIS OF (6R)- AND (6S)-FLUOROSHIKIMIC ACIDS

J. Coggins, E. Parker, C. Abell, 1995 .

The folding of the bifunctional TRP3 protein in yeast is influenced by a translational pause which lies in a region of structural divergence with Escherichia coli indoleglycerol-phosphate synthase.

A. Brown, J. Coggins, J. Boyle, 1994, European journal of biochemistry.

[44] 3-Phosphoshikimate 1-carboxyvinyltransferase from Pisum sativum

J. Coggins, D. Mousdale, 1987 .

The complete amino acid sequence of Escherichia coli 5‐enolpyruvylshikimate 3‐phosphate synthase

J. Coggins, K. Duncan, A. Lewendon, 1984 .

The stoichiometry of binding of flavin mononucleotide (FMN) hydroquinone to Escherichia coli chorismate synthase

J. Coggins, T. Hawkes, M. Ramjee, 1993 .

Chorismate synthase. Pre-steady-state kinetics of phosphate release from 5-enolpyruvylshikimate 3-phosphate.

J. Coggins, T. Hawkes, D. Mousdale, 1990, The Biochemical journal.

The overexpression, purification and complete amino acid sequence of chorismate synthase from Escherichia coli K12 and its comparison with the enzyme from Neurospora crassa.

J. Coggins, G. Millar, P. White, 1988, The Biochemical journal.

Electroporation of lymphoid cells: factors affecting the efficiency of transfection.

J. Coggins, D. Spandidos, M. L. Anderson, 1991, Journal of biochemical and biophysical methods.

The two types of 3-dehydroquinase have distinct structures but catalyze the same overall reaction

Lindsay Sawyer, Igor Polikarpov, N. Isaacs, 1999, Nature Structural Biology.

The structure of Escherichia coli ATP-phosphoribosyltransferase: identification of substrate binding sites and mode of AMP inhibition.

G. McDermott, J. Coggins, A. Lapthorn, 2004, Journal of molecular biology.

Intramolecular ionic interactions of lysine residues and a possible folding domain in fructose diphosphate aldolase.

J. Coggins, R. Perham, J. Lambert, 1977, The Biochemical journal.

Phosphoglycerate mutase from Streptomyces coelicolor A3(2): purification and characterization of the enzyme and cloning and sequence analysis of the gene

N. C. Price, J. Coggins, I. Hunter, 1992, Journal of bacteriology.

The Saccharomyces cerevisiae ARO1 gene An example of the co‐ordinate regulation of five enzymes on a single biosynthetic pathway

J. Coggins, K. Duncan, R. Edwards, 1988, FEBS letters.

Evidence for an ancestral core structure in nucleotide-binding proteins with the type A motif.

J. Coggins, E. Milner-White, I. Anton, 1991, Journal of molecular biology.

Comparative analysis of the QUTR transcription repressor protein and the three C-terminal domains of the pentafunctional AROM enzyme.

J. Coggins, J. Moore, A. Hawkins, 1996, The Biochemical journal.

The Impact of Recombinant DNA Techniques on the Study of Enzymes

J. Coggins, 1989 .

The complete amino acid sequence of 3‐dehydroquinate synthase of Escherichia coli K 12

J. Coggins, G. Millar, 1986 .

The shikimate pathway and its branches in apicomplexan parasites.

J. Finnerty, R. Lyons, J. Dame, 2002, The Journal of infectious diseases.

Aldolase-like imine formation in the mechanism of action of phosphonoacetaldehyde hydrolase.

J. Coggins, H. Dixon, J. L. La Nauze, 1977, The Biochemical journal.

Stabilization of the shikimate pathway enzyme dehydroquinase by covalently bound ligand.

N. C. Price, J. Coggins, C. Kleanthous, 1991, The Journal of biological chemistry.

The three-dimensional structure of shikimate kinase.

T. Krell, J. Coggins, A. Lapthorn, 1998, Journal of molecular biology.

Product-induced stabilization of tertiary and quaternary structure in Escherichia coli dehydroquinase.

N. C. Price, J. Coggins, C. Kleanthous, 1994, The Journal of biological chemistry.

Biochemical and X‐ray crystallographic studies on shikimate kinase: The important structural role of the P‐loop lysine

N. C. Price, T. Krell, J. Coggins, 2001, Protein science : a publication of the Protein Society.

Purification and characterization of bifunctional dehydroquinase-shikimate: NADP oxidoreductase from pea seedlings

J. Coggins, D. Mousdale, M. S. Campbell, 1987 .

Evidence from peptide mapping for a human renin zymogen

J. Coggins, S. Chaudhuri, G. McIntyre, 1984, FEBS letters.

Experiences with the shikimate-pathway enzymes as targets for rational drug design.

J. Coggins, D. Robinson, C. Abell, 2003, Biochemical Society transactions.

Chemical modification monitored by electrospray mass spectrometry: a rapid and simple method for identifying and studying functional residues in enzymes.

T. Krell, J. Coggins, A. Pitt, 2009, The journal of peptide research : official journal of the American Peptide Society.

Localization of the Active Site of Type II Dehydroquinases

T. Krell, J. Coggins, M. Horsburgh, 1996, The Journal of Biological Chemistry.

Structural and enzymological analysis of the interaction of isolated domains of cytochrome P‐450 BM3

N. C. Price, J. Coggins, A. Munro, 1994, FEBS letters.

The pentafunctional arom enzyme of Saccharomyces cerevisiae is a mosaic of monofunctional domains.

J. Coggins, K. Duncan, R. Edwards, 1987, The Biochemical journal.

Evidence for a novel class of microbial 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase in Streptomyces coelicolor A3(2), Streptomyces rimosus and Neurospora crassa.

J. Coggins, G. Walker, I. Hunter, 1996, Microbiology.

The purification and molecular properties of the tryptophan-sensitive 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase from Neurospora crassa.

J. Coggins, G. Nimmo, 1981, The Biochemical journal.

Site Directed Mutagenesis as a Tool to Study Enzyme Catalysis

J. Coggins, 1989 .

α‐Bungarotoxin binding to the nicotinic acetylcholine receptor is inhibited by two distinct subpopulations of anti‐receptor antibodies

J. Coggins, J. Gairns, T. Barkas, 1982 .

A modified synthesis of -N-carbobenzoxy-L-lysine and the preparation and analysis of mixtures of -N-methyllysines.

J. Coggins, G. J. Moore, N. Benoiton, 1971, Canadian Journal of Biochemistry.

Vinyl fluoride as an isoelectronic replacement for an enolate anion: inhibition of type II dehydroquinases.

J. Coggins, C. Abell, M. Frederickson, 2002, Chemical communications.

Reply: Shikimate pathway in apicomplexan parasites

J. Finnerty, D. Chakrabarti, F. Roberts, 1999, Nature.

Deletions, fusions and domain rearrangements.

J. Coggins, 1991, Current opinion in biotechnology.

The role of tryptophan 97 of cytochrome P450 BM3 from Bacillus megaterium in catalytic function. Evidence against the 'covalent switching' hypothesis of P-450 electron transfer.

J. S. Miles, N. C. Price, J. Coggins, 1994, The Biochemical journal.

Nanomolar Competitive Inhibitors of Mycobacterium tuberculosis and Streptomyces coelicolor Type II Dehydroquinase

J. Coggins, A. Hawkins, C. González‐Bello, 2007, ChemMedChem.

Synthesis of 4-deoxyquinic, 4-deoxyshikimic and 4-deoxy-3-dehydroshikimic acids

J. Coggins, A. Hawkins, C. González‐Bello, 1999 .

The purification of shikimate dehydrogenase from Escherichia coli.

J. Coggins, S. Chaudhuri, 1985, The Biochemical journal.

Analysis of the structural stability of the multidomain enzyme flavocytochrome P-450 BM3.

N. C. Price, J. Coggins, A. Munro, 1996, Biochimica et biophysica acta.

Characterization of the type I dehydroquinase from Salmonella typhi.

I. Charles, N. C. Price, J. Coggins, 1993, The Biochemical journal.

Identification of domains responsible for signal recognition and transduction within the QUTR transcription repressor protein.

J. Coggins, A. Hawkins, H. Lamb, 2000, The Biochemical journal.

The purification of 5‐enolpyruvylshikimate 3‐phosphate synthase from an overproducing strain of Escherichia coli

J. Coggins, K. Duncan, A. Lewendon, 1984, FEBS letters.

Mutagenesis of Active Site Residues in Type I Dehydroquinase from Escherichia coli

J. Coggins, C. Kleanthous, A. Leech, 1995, Journal of Biological Chemistry.

Rational design of new bifunctional inhibitors of type II dehydroquinase.

M. Toscano, J. Coggins, C. Abell, 2005, Organic & biomolecular chemistry.

Design, synthesis and evaluation of bifunctional inhibitors of type II dehydroquinase.

M. Toscano, J. Coggins, C. González‐Bello, 2003, Organic & biomolecular chemistry.

Some kinetic properties of the tryptophan-sensitive 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase from Neurospora crassa.

J. Coggins, G. Nimmo, 1981, The Biochemical journal.

Effects of salts on the function and conformational stability of shikimate kinase.

N. C. Price, J. Coggins, D. Clarke, 2003, Biochimica et biophysica acta.

The refolding of type II shikimate kinase from Erwinia chrysanthemi after denaturation in urea.

N. C. Price, J. Coggins, D. Clarke, 2002, European journal of biochemistry.

Kinetic analysis of the interaction between the QutA and QutR transcription‐regulating proteins

J. Coggins, A. Hawkins, H. Lamb, 2002, Proteins.

Twists and turns: a tale of two shikimate-pathway enzymes.

J. Coggins, D. Svergun, K. Watson, 2003, Biochemical Society transactions.

Different mechanistic and stereochemical courses for the reactions catalysed by type I and type II dehydroquinases

J. Coggins, A. Hawkins, C. Kleanthous, 1993 .

Inhibition of chorismate synthase by (6R)- and (6S)-6-fluoro-5-enolpyruvylshikimate 3-phosphate

S. Balasubramanian, J. Coggins, C. Abell, 1991 .

Reversible alkylation of an active site methionine residue in dehydroquinase.

J. Coggins, C. Kleanthous, 1990, The Journal of biological chemistry.

The characterisation of the shikimate pathway enzyme dehydroquinase from Pisum sativum

J. Coggins, I. Anton, B. Dunbar, 1994, FEBS letters.

Purification and characterization of a dual function 3-dehydroquinate dehydratase from Amycolatopsis methanolica.

J. Coggins, J. Vrijbloed, G. Hessels, 1992, Journal of general microbiology.

Crystallization of a type I 3-dehydroquinase from Salmonella typhi.

I. Charles, J. Coggins, J. Moore, 1992, Journal of molecular biology.

A eukaryotic repressor protein, the qa-1S gene product of Neurospora crassa, is homologous to part of the arom multifunctional enzyme.

J. Coggins, I. Anton, K. Duncan, 1987, Journal of molecular biology.

[42] The arom multifunctional enzyme from neurospora crassa

J. Coggins, S. Chaudhuri, G. Nimmo, 1987 .

Alkane metabolism by cytochrome P450 BM3.

J. Coggins, A. Munro, J. Lindsay, 1993, Biochemical Society transactions.

Identification of the active-site lysine residues of two biosynthetic 3-dehydroquinases.

J. Coggins, S. Chaudhuri, L. Graham, 1991, The Biochemical journal.

Sequencing and overexpression of the Escherichia coli aroE gene encoding shikimate dehydrogenase.

J. Coggins, I. Anton, 1988, The Biochemical journal.

High-performance liquid chromatography of shikimate pathway intermediates

J. Coggins, D. Mousdale, 1985 .

Isolation of a bifunctional domain from the pentafunctional arom enzyme complex of Neurospora crassa.

J. Coggins, D. Smith, 1983, The Biochemical journal.

Spectrophotometric detection of a modified flavin mononucleotide (FMN) intermediate formed during the catalytic cycle of chorismate synthase

J. Coggins, T. Hawkes, M. Ramjee, 1991 .