Homogenous crystalline phosphoglycerate phosphomutase of high activity. A simple method for lysis of yeast

The amino acid sequence of the aspartate aminotransferase from baker's yeast (Saccharomyces cerevisiae)

1. The single (cytosolic) aspartate aminotransferase was purified in high yield from baker's yeast (Saccharomyces cerevisiae). 2. Amino-acid-sequence analysis was carried out by digestion of the protein with trypsin and with CNBr; some of the peptides produced were further subdigested with Staphylococcus aureus V8 proteinase or with pepsin. Peptides were sequenced by the dansyl-Edman method and/or by automated gas-phase methods. The amino acid sequence obtained was complete except for a probable gap of two residues as indicated by comparison with the structures of counterpart proteins in other species. 3. The N-terminus of the enzyme is blocked. Fast-atom-bombardment m.s. was used to identify the blocking group as an acetyl one. 4. Alignment of the sequence of the enzyme with those of vertebrate cytosolic and mitochondrial aspartate aminotransferases and with the enzyme from Escherichia coli showed that about 25% of residues are conserved between these distantly related forms. 5. Experimental details and confirmatory data for the results presented here are given in a Supplementary Publication (SUP 50164, 25 pages) that has been deposited at the British Library Document Supply Centre, Boston Spa. Wetherby, West Yorkshire LS23 7 BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1991) 273, 5.

The unfolding and refolding of glutamate dehydrogenases from bovine liver, baker's yeast and Clostridium symbosium

The unfolding behaviour of the hexameric glutamate dehydrogenases from bovine liver, Clostridium symbosium and baker's yeast in solutions of guanidinium chloride (GdnHCl) was studied. Changes in Mr studied by light-scattering indicate that, in each case, the hexamer dissociates to form trimers, which then dissociate to monomers at higher concentrations of GdnHCl. Dissociation to trimers is accompanied by a reversible loss of enzyme activity, but no gross structural changes can be detected by fluorescence or c.d. Dissociation to monomers is accompanied by large structural changes, and the loss of activity cannot be reversed by dilution. The parallel behaviour of all three enzymes shows that the previously noted inability of the isolated subunits of the bovine liver enzyme to refold [Bell & Bell (1984) Biochem. J. 217, 327-330] is not a result of any modification of the enzyme as a result of import into mitochondria, since the C. symbosium and baker's-yeast enzymes do not undergo any such post-translational translocation.

Purification and structural comparisons of the cytosolic and mitochondrial fumarases from baker's yeast

1. The cytosolic and mitochondrial fumarases (EC 4.2.1.2) from baker's yeast (Saccharomyces cerevisiae) have been purified to homogeneity. 2. Subunit molecular weights for the cytosolic and mitochondrial isoenzymes were 53,000 and 48,000 respectively. 3. Peptide maps obtained after digestion of the two isoenzymes with trypsin were almost identical but showed significant small differences. The same was true of peptide maps obtained after digestion with the glutamic acid-specific proteinase from S. aureus.

The susceptibility towards proteolysis of intermediates during the renaturation of yeast phosphoglycerate mutase

The renaturation of the tetrameric enzyme phosphoglycerate mutase from baker's yeast after denaturation in guanidinium chloride was studied. Three proteinases (trypsin, chymotrypsin and thermolysin) cause extensive loss of activity of samples taken during the early stages of refolding. As judged by SDS/polyacrylamide-gel electrophoresis, the proteinases cause substantial degradation of the polypeptide chain with no evidence for large quantities of fragments of Mr greater than 6500. These data suggest that the early intermediates in the refolding, especially the folded monomer, possess a number of sites that are susceptible to proteolysis.

The phosphonomethyl analogue of 3-phosphoglycerate is a potent competitive inhibitor of phosphoglycerate mutases

The phosphonomethyl analogue of 3-phosphoglycerate (2-hydroxy-4-phosphonobutanoate) is a potent competitive inhibitor of cofactor-dependent phosphoglycerate mutase from yeast and of cofactor-independent phosphoglycerate mutase from wheat germ. For the yeast enzyme Ki is 1.3 mM (Km for substrate is 0.71 mM); for the wheatgerm enzyme Ki is 18 mM (Km for substrate is 0.86 mM). This analogue should be a useful tool for n.m.r. spectroscopic studies on the mechanism of action of the two mutases. The arsonomethyl analogue of 3-phosphoglycerate (4-arsono-2-hydroxybutanoate) was a relatively poor inhibitor.

Purification and properties of tryptophan synthase from baker's yeast (Saccharomyces cerevisiae)

Tryptophan synthase was purified from baker's yeast. The purified enzyme exhibited one band on polyacrylamide-gel electrophoresis, had no detectable N-terminal amino acid and C-terminal alanine. The amino acid composition was close to that predicted by recent studies on the DNA sequence of the structural gene for the enzyme. Kinetic parameters for the following three activities were measured: indole-serine condensation, indolylglycerol phosphate lyase and the overall reaction of serine with 1-(indol-3-yl)glycerol 3-phosphate. The Km for indole was much lower than suggested by previous investigations, and the value of 11 microM was measured by a fluorimetric assay.

An improved automated method for the measurement of red cell 2,3-diphosphoglycerate

A modified automated colorimetric micromethod for the determination of red cell 2,3-diphosphoglycerate (2,3-DPG) adapted from that of Grisolia et al (1969) is described. In the modified method, ethylenediaminetetra-acetic acid (EDTA) is not used and consequently concentrations of several reagents are changed. During the development of the method it was found that the presence of EDTA, either in the blood or in reagents, consistently reduced the measured value of 2,3-DPG by 15%. This effect of EDTA, not previously recognized, is independent of the EDTA concentration within the range of 5 to 50 mmol/1 and is at present unexplianed. In normal subjects (41 men and 30 women) the mean red cell 2,3-DPG was 14-5 mol/g haemoglobin (range 12-1-18-1 mol/g haemoglobin). There was no significant difference in 2,3-DPG concentrations between male and female subjects.

Subunit structure and multifunctional properties of yeast phosphoglyceromutase

1. A new and efficient method for preparation of pure phosphoglyceromutase from baker's yeast (Saccharomyces cerevisiae) is described. Proteolytic alterations of the enzyme during extraction can be minimized by grinding the dried yeast with aluminium oxide at low temperature. 2. Yeast phosphoglyceromutase contains four highly similar, probably idential subunits of molecular weight 28000, a conclusion based on the following observations. Polyacrylamide gel electrophoresis containing dodecylsulphate or urea gives a single band, indicating that the enzyme is composed of four subunits similar in their molecular weight and net charge. Cyanogen bromide cleavage and tryptic digestion of the enzyme yield the number of peptides expected for identical subunites from the amino acid composition analysis. 3. The purified phosphoglyceromutase preparation has bisphosphoglyceromutase activity synthesizing 2,3-bisphosphoglycerate from 1,3-bisphosphoglycerate and 3-phosphoglycerate. It has been reported that yeast phosphoglyceromutase catalyzes the hydrolysis of 2,3-bisphosphoglycerate at the same active site which catalyzes the phosphoglyceromutase reaction [Sasaki, R. et al (1971) Biochim. Biophys, Acta, 227, 584-594, 595-607]. Immunological studies and chemical modification experiments indicate that bisphosphoglyceromutase activity also is due to the phosphoglyceromutase protein and involves amino groups which have been shown to be essential for the other two activities.

An improved procedure for the isolation of 3-phosphoglycerate kinase from yeast

3-Phosphoglycerate kinase has been isolated from yeast by a new procedure. Over 1g was obtained from 450g of granulated baker's yeast; it had a specific activity of up to 940units/mg at 30 degrees C. Six distinct crystalline forms have been grown, at least one of these being suitable for X-ray diffraction studies. The crystalline preparation is pure, judged by starch-gel or sodium dodecyl sulphate-polyacrylamide-gel electrophoresis; the latter method indicating that the enzyme is monomeric, with a molecular weight near to 50000.