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L F Hass

Publications and source records attributed to L F Hass.

At least 19 recordsLinked to original sources
PubMed1987

2,3-diphosphoglycerate phosphatase activity of phosphoglycerate mutase: stimulation by vanadate and phosphate.

The binding of inorganic vanadate (Vi) to rabbit muscle phosphoglycerate mutase (PGM), studied by using 51V nuclear magnetic resonance spectroscopy, shows a sigmoidal dependence on vanadate concentration with a stoichiometry of four vanadium atoms per PGM molecule at saturating [Vi]. The data are consistent with binding of one divanadate ion to each of the two subunits of PGM in a noncooperative manner with an intrinsic dissociation constant of 4 X 10(-6) M. The relevance of this result to other studies which have shown that the Vi-stimulated 2,3-diphosphoglycerate (2,3-DPG) phosphatase activity of PGM has a sigmoidal dependence on [Vi] with a Hill coefficient of 2.0 is discussed. At pH 7.0, inorganic phosphate has little effect on the 2,3-DPG phosphatase activity of PGM, even at concentrations as high as 50 mM. Similarly, 25 microM Vi has little effect on the phosphatase activity. However, in the presence of 25 microM Vi, a phosphate concentration of 20 mM increases the phosphatase activity by more than 3-fold. This behavior is rationalized in terms of activation of the phosphatase activity by a phosphate/vanadate mixed anhydride. This interpretation is supported by the observation of strong activation of the phosphatase activity by inorganic pyrophosphate. A molecular mechanism for the observed effects of vanadate is proposed, and the relevance of this study to the possible use of vanadate as a therapeutic agent for the treatment of sickle cell anemia is discussed.

Animals↗
PubMed1986

The catalytic bimodality of mammalian phosphoglycerate mutase.

Rabbit muscle phosphoglycerate mutase, presumed to manifest an absolute cofactor requirement for activity, has been found to express catalysis (3 +/- 1% of optimum) in the absence of added D-glycerate-2,3-P2. Isotope experiments indicate that this catalysis proceeds through a binary phosphoryl enzyme-glycerate intermediate which dissociates into free enzyme and monophosphoglycerate. 32P-Labeled phosphoglycerate mutase is formed by reaction with either D-32P-glycerate-3-P or D-U32P-glycerate-2,3-P2. In each case, the acid lability and alkali stability of the covalent adduct, phosphoenzyme, is consistent with a phosphohistidyl residue having been formed within the active site. D-[U-14C]Glycerate reacts with phosphoenzyme to generate D-[U-14C]monophosphoglycerate which, in turn, can react further with phosphoenzyme to yield D-[U-14C]glycerate-2,3-P2. The pH profile for the cofactor-independent activity exhibits an optimum at 6.0 as opposed to 7.0 when D-glycerate-2,3-P2 is present in the reaction medium. Bisubstrate kinetics (pH 7.0, 23 degrees C) with D-glycerate-3-P concentration as the variable, yields a family of reciprocal plots which is in accord with a modified ping-pong mechanism when D-glycerate-2,3-P2 concentrations are greater than 10(-1) Km (where Km = 0.33 microM). Progressively diminishing concentrations (much less than Km) of D-glycerate-2,3-P2 produce curvilinear reciprocal plots that approach linearity as a limit in accordance with single substrate kinetics.

2,3-Diphosphoglycerate↗
PubMed1986

Wheat germ phosphoglycerate mutase: evidence for a metalloenzyme.

Wheat germ phosphoglycerate mutase, exposed to 3.4 M guanidinium chloride at 22 degrees C and pH 7.8, slowly undergoes time-dependent inactivation which can be fully reversed by adding excess Co2+ or Mn2+ to a 50-fold dilution of the denaturing medium. Titration of the denatured enzyme with either Co2+ or Mn2+ shows that wheat germ mutase preferentially binds Co2+. Assuming 1:1 complexation between metal atom and protein, the apparent dissociation constants (Kd) for E Co2+ and E Mn2+ at 22 degrees C and pH 8.7 are approximately 1.06 and 1.84, respectively. Other metal atoms (e.g., Cr2+, Cu2+, Fe2+, Fe3+, Mg2+, and Ni2+) have no effect in restoring the apoenzyme's catalytic activity. At low concentrations (0.11-0.23 mM) Zn2+ partially restores activity, but promotes protein precipitation at elevated concentrations. Evidence suggests that all bisphosphoglycerate-independent phosphoglycerate mutases require either an intra- or an extramolecular metal atom in order to function. Attempts to characterize wheat germ mutase as a glycoprotein have yielded negative results.

Bisphosphoglycerate Mutase↗
PubMed1986

MATCH-UP/MATRIX: a microcomputer program designed to search for protein primary structure homology.

MATCH-UP/MATRIX is a program designed to aid the investigator interested in determining primary protein structure. It is written in Applesoft BASIC for the Apple IIe microcomputer. MATCH-UP will survey any set of proteinaceous materials for amino acid sequence homology; however, it is primarily intended to compare the structures of newly sequenced peptides with the established structure of a protein with suspected homology. Any peptide-to-protein alignment which shows a homology greater than or equal to the percentage specified by the user will result in output. MATRIX will compare the sequences of two proteins (peptides) in whatever alignment specified by the user and is intended to spot insertions and/or deletions between structures.

Algorithms↗
PubMed1985

Wheat germ phosphoglycerate mutase: purification, polymorphism, and inhibition.

An improved method for purifying the bisphosphoglycerate-independent phosphoglycerate mutase from wheat germ has been devised. The method yields enzyme with a specific activity of 2,300 units/mg in 0.1 M Tris-C1 at pH 8.7 and 30 degrees C. Electrophoresis on electrofocusing and analytical polyacrylamide gels reveals only one protein band (pI = 7.3); however, under denaturing conditions (sodium dodecyl sulfate polyacrylamide gel electrophoresis), two prominent enzyme forms, with molecular masses of 63 and 74 kDa, manifest themselves along with several minor, high molecular mass components (126-141 kDa). Non-denaturing exclusion chromatography shows that both major species are catalytically active, and suggests that each species is capable of participating in reversible monomer/dimer association. Wheat germ mutase is inhibited by time-dependent reactions involving either polydentate chelators or sulfhydryl reagents.

Bisphosphoglycerate Mutase↗
PubMed1978

Evidence for structural homology between human red cell phosphoglycerate mutase and 2,3-bisphosphoglycerate synthase.

Previous reports have suggested the possibility of extensive structural homology between human erythrocyte bisphosphoglycerate synthase (glycerate-1,3-P2 leads to glycerate-2,3-P2) and phosphoglycerate mutase (glycerate-3-P in equilibrium glycerate-2-P). This study lends credence to that conjecture through comparative physicochemical investigations involving peptide mapping, circular dichroism, and immunological techniques. The data indicate that despite differences in function, both enzymes apparently manifest a high degree of similarity in primary, secondary, and tertiary structure. Mapping data also indicate that each protein is comprised of two apparently identical subunits.

Bisphosphoglycerate Mutase↗
PubMed1976

Isolation and partial characterization of monophosphoglycerate mutase from human erythrocytes.

Monophosphoglycerate mutase has been purified to homogeneity from outdated human erythrocytes as indicated by exclusion chromatography, polyacrylamide gel electrophoresis, and equilibrium centrifugation. Occasionally, the recommended purification procedure yields a small amount (3% or less) of a single extraneous protein which can be deleted from the enzyme preparation by employing an additional purification step. The native enzyme has a molecular weight of 54,000 to 56,000 as determined by equilibrium centrifugation and exclusion chromatography. Disc gel electrophoresis in the presence of sodium dodecyl sulfate yields a single protein band with a molecular weight of 28,600, indicating that the native macromolecule is a dimer composed of subunits of similar mass. Homogeneous monophosphoglycerate mutase is free of diphosphoglycerate mutase, enolase, and nonspecific phosphatase activities; however, the enzyme manifests intrinsic 2,3-diphospho-D-glycerate phosphatase activity as shown by thermal denaturation studies. The diphosphatase activity is stimulated by PPi and glycolate-2-P, but is inhibited by Cl-, HSO3-, and Pi. The pH optimum for both the diphosphatase and the mutase is 6.8. The Km for 2,3-diphospho-D-glycerate in the phosphatase reaction is 82 muM at 37 degrees and pH 7.2. The amino acid composition of homogeneous monophosphoglycerate mutase is given.

Amino Acids↗
PubMed1976

The isolation and partial characterization of diphosphoglycerate mutase from human erythrocytes.

Diphosphoglycerate mutase has been purified to homogeneity from outdated human erythrocytes. The native enzyme has a molecular weight of 57 000 as determined by equilibrium centrifugation and exclusion chromatography. Disc gel electrophoresis in the presence of sodium dodecyl sulfate yields a single protein band with a molecular weight of about 26 500, indicating that diphosphoglycerate mutase is comprised of two subunits of similar mass. The enzyme exhibits the following intrinsic activities: diphosphoglyceratemutase, monophosphoglycerate mutase, and 2,3-diphosphoglycerate phosphatase. The latter activity is enhanced in the presence of either organic or inorganic anions. Glycolate-2-P, particularly, has a profound activating effect. Nonspecific phosphatase and enolase activities are absent. The enzyme has an extinction coefficient at 280 nm of 1.65 cm2/mg. The amino acid composition of the homogeneous protein has been determined.

Amino Acids↗