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Y H Edwards

Publications and source records attributed to Y H Edwards.

At least 91 records · Page 5Linked to original sources
PubMed1983

A genetic characterization of the human diaphorase-4 deficiency.

Analyses of DIA4 activity in cultured cells from a random population, a small family and human/rodent somatic cell hybrids support the view that the quantitative polymorphism of human DIA4 can be attributed to the segregation of a 'low activity' allele. (1) In a series of lymphoblastoid cell lines from 52 unrelated individuals, three lines were found which did not exhibit DIA4 after electrophoresis and showed low levels of NADPH diaphorase activity. The frequency (6%) of the DIA4 'absent' phenotype is close to that (4%) determined previously by analysis of post-mortem tissue. (2) Cultured fibroblasts from a small family in which the DIA 4 low-activity allele was apparently segregating were analysed. The NADPH diaphorase activity of the propositus (DIA4 'absent' phenotype) was very low (less than 6% of normal). He also exhibited very weak DIA4 isozymes of unusual electrophoretic mobility. The activity of both parents and sib was about half the normal level, suggesting that these individuals are heterozygous for the low-activity allele. (3) Analysis of a series of independent human/hamster hybrid clones, made using a human parent heterozygous for phosphoglycolate phosphatase (PGP) and DIA4, suggested that in this particular individual the DIA 4 low-activity allele segregates with the PGP 2 allele. However, there were 2 hybrids amongst a total of 16 which gave discordant results and these are to be the subject of further analysis by subcloning.

Alleles↗
PubMed1983

A sperm-specific enolase.

An unusual enolase isoenzyme, ENO S, was found in human, ram and mouse spermatozoa. This isoenzyme is unique to spermatozoa and distinguished from the somatic enolases ENO 1, ENO 2 and ENO 3 by electrophoretic mobility, high thermostability and ability to undergo structural alteration at high temperatures. The pattern of expression of ENO S during sperm differentiation suggests that this isoenzyme is synthesized relatively late in the presence of a haploid genome.

Animals↗
PubMed1982

Human mitochondrial glycerol phosphate dehydrogenase (GPDm) isozymes.

1. A hydrophobic/phospholipid electrophoretic system has been devised which makes possible the analysis of human mitochondrial glycerol phosphate dehydrogenase (E.C. 1.1.99.5. GPDM). 2. GPDM has a wide tissue distribution in both adult and foetal life and is active in cultured lymphoblastoid cells and fibroblasts but is absent from red cells. 3. The solubilization procedure does not significantly alter the kinetic properties of the enzyme (Km alpha-glycerophosphate = 0.04-0.07 M, Km PMS = 0.19-0.35 mM) but the soluble form is less thermostable. 4. Comparisons of physicochemical characteristics, tissue distribution and coenzyme requirement point to a separate genetic determination and low level of evolutionary relatedness between GPDM and its cytosolic counterpart GPDS.

Animals↗
PubMed1982

Zinc and carbonic anhydrase III distribution in mammalian muscle.

Zinc and carbonic anhydrase III measurement in human and rat muscle extracts indicate that: 1. About one fifth of zinc in human soleus is associated with carbonic anhydrase III isozyme, and even higher levels of zinc and carbonic anhydrase III are found in rat soleus, where about one half of the zinc is in carbonic anhydrase III. Other muscle was also analysed in a similar way, (see text). Heart is notable in containing lower levels of zinc but negligible carbonic anhydrase III. 2. Treatment of muscle with water or phosphate solutions showed that all the carbonic anhydrase III was water extractable, whereas significant zinc remained bound, but was partially extractable by phosphate solutions. 3. Dialysis of muscle extracts showed that whilst some zinc was dialysable, there was no significant contribution from the carbonic anhydrase III in the dialysed extract. EDTA enhanced the release of dialysable zinc from muscle extract. These findings are discussed in relation to muscle disease.

Animals↗
PubMed1982

The genetic relationship between the human foetal acetylesterase ESA7 and the adult acetylesterase ESA5.

(1) There are very few clear examples among human enzymes of foetal isozymes which are the products of foetal specific gene loci. Earlier studies had pointed to the foetal brain esterase ESA7 as a probable example. (2) Detailed biochemical investigation of partially purified human adult brain ESA5 and the foetal esterase ESA7 has revealed a close resemblance in the biochemical properties of these two isozymes. In addition to similarities in substrate specificity and inhibition sensitivity the two esterases have the same molecular size (c. 57,000), are both relatively unstable at 37 degrees C and show decreased anodal electrophoretic mobility after storage at 20 degrees C. Furthermore there was suggestive evidence that ESA7 and ESA5 may be interconvertible. (3) A variant esterase isozyme pattern, which shows unusual features of both ESA7 and ESA5, was found in a survey of 120 foetal brains. This variant pattern is consistent with a monomeric structure for both esterases and points strongly to a common genetic determination.

Acetylesterase↗
PubMed1982

Isozyme patterns and protein profiles in neuromuscular disorders.

The isozyme patterns of six different enzymes and the polypeptide profiles of soluble proteins have been examined in muscle biopsy specimens from 74 patients with a wide variety of neuromuscular disorders. About half of the samples showed unusual features in at least one, and often several, of the enzymes and proteins tested. The extent of the biochemical abnormalities was roughly proportional to the severity of the disorders. In all cases the unusual isozymes and polypeptide profiles seemed to reflect a reversion to the fetal pattern of gene expression. However, this change appeared to occur in extant muscle and was not dependent on the appearance of new muscle fibres. Among the enzymes, phosphoglycerate mutase followed by creatine kinase appeared to be the most sensitive index of muscle disorder. The extent of the change in the muscle creatine kinase isozyme pattern was not correlated with the levels of serum creatine kinase activity.

Acid Phosphatase↗
PubMed1980

Human FAD-dependent NAD(P)H diaphorase.

A newly discovered human diaphorase, designated diaphorase-4, which accounts for a major part of the diaphorase activity of most tissues but does not occur in erythrocytes, is described. In contrast with other human diaphorases, it is dependent on FAD for activity after electrophoresis, inhibited by low concentrations of dicoumarol and shows a marked affinity for Cibacron Blue. The molecular weight was estimated to be 49000 +/- 1800 by gel filtration. Diaphorase-4 appears to show person-to-person quantitative variation, so that about 4% of the population lack appreciable enzyme activity, but it is not yet clear whether this variation is of genetic or non-genetic origin.

Anthracenes↗
PubMed1979

A comparison of the biochemical properties of the human diaphorase (DIA3) isozymes determined by the common alleles DIA13, DIA23 and DIA33.

(1) Various buffer systems for the starch gel electrophoresis of human diaphorase isozymes have been explored. Electrophoresis in a Tris/Borate system at pH 8.6 which includes 70 micron NADH in the gel and cathodal electrode buffers, provides good resolution of the six DIA3 phenotypes previously resolved by isoelectric focusing. (2) The variant genes DIA13, DIA23 and DIA33 occur with frequencies of about 0.76, 0.23 and 0.01 respectively in the English population. (3) The isozymes determined by the least common gene, DIA33, are markedly different from the isozymes determined by DIA13 and DIA23 in their relatively low heat stability, high affinity for Blue Sepharose and slow anodal electrophoretic mobility in buffer systems containing borate. The DIA3 1 and DIA3 2 isozymes are similar to one another in these characteristics.

Alleles↗
PubMed1979

The genetic determination of fumarase isozymes in human tissues.

(1) A method for the starch gel electrophoresis of human fumarase has been devised which resolves two groups of isozymes: one group (FHM) is associated with the mitochondria, the other (FHS) is cytosolic. (2) Tissue to tissue variation in the complexity of the isozyme patterns and the examination of red cells fractionated according to their age by density gradient centrifugation suggest that the least anodal isozymes of the FHS group and ofthe FHM group are modified in vivo with the generation of several secondary isozymes. (3) Red cells, which display only FHS isozymes, were screened from 776 European and 100 Nigerian individuals and a single electrophoretic variant (phenotype FH 2-1) was identified in a middle-aged male from England. The same variant was identified in a paternal aunt and the data suggest that the variant repressents heterozygosity for the common (FH1) allele and a rare variant (FH2) allele at an autosomal locus. (4) Fibroblasts and white cells from the FH 2-1 individual showed variation in the FHM and FHS isozymes indicating that the mitochondrial and the soluble forms of fumarase are determined at the same structural locus.

Centrifugation, Density Gradient↗
PubMed1979

Further characterization of the human fumarase variant, FH 2--1.

1. Further investigation of fumarase using lymphoblastoid cells derived from an individual of the FH 2--1 phenotype has confirmed that the mitochondrial (FHM) and soluble (FHS) forms of fumarase are determined at the same structural locus. 2. The FH 2--1 variant is associated with enzyme deficiency: c. 70% of normal in lymphoblastoid cells and c. 20% of normal in red cells. 3. The pH optimum and apparent Michaelis constant of the variant fumarase were normal but heat-inactivation studies suggest that the isozymes containing polypeptides determined by the variant allele are unstable.

Cell Line↗
PubMed1978

Developmental changes in the protein profiles of human cardiac and skeletal muscle.

1. The use of SDS electrophoresis as a tool for the analysis of development processes in man has been evaluated. 2. The protein profiles of cardiac and skeletal muscle from foetal (10--24 weeks gestation) infant and adult specimens have been analysed and striking developmental changes were found which involved all the major proteins. 3. Before 20 weeks gestation the soluble protein profile of skeletal muscle appears to consist largely of extracellular proteins. 4. Myoglobin was found in foetal cardiac muscle from 20 weeks gestation but was not demonstrable in foetal (greater than 24 weeks) skeletal muscle. Foetal and adult myoglobin were indistinguishable. 5. A limited survey of the protein patterns of brain, liver and kidney was carried out. In general these tissues show less developmental change than skeletal or cardiac muscle.

Adult↗
PubMed1977

Polymorphism and the subunit structure of enzymes: a contribution to the neutralist-selectionist controversy.

The occurrence of polymorphism in a series of 87 different loci coding for enzyme structure in human populations has been related to the size and the number of subunits in the corresponding enzymes. Polymorphic and nonpolymorphic enzymes did not differ on average in subunit size. However, multimeric enzymes showed a significantly lower incidence of polymorphism than didmonomeric enzymes. A particularly low incidence of polymorphism was noted among multimeric enzymes in which interlocus molecular hybrids occur. The findings are discussed in terms of the "neutralist" and "selectionist" hypotheses of polymorphism.

Enzymes↗
PubMed1977

The distribution of subunit sizes of soluble proteins in human tissues.

1. The distribution of subunit sizes of soluble proteins in human tissues has been examined by the technique of gel filtration chromatography followed by SDS polyacrylamide gel electrophoresis. 2. Up to 101 different polypeptides were identified. These appear to represent primarily the substituent polypeptides of easily solubilized 'non-enzyme' proteins. 3. The subunit sizes ranged between 7000 and 270000 and the distribution was continuous unimodal and skewed. The mean size was estimated at 54 600+/-42 900. 4. The distribution of subunit sizes and the overall mean were found to be similar to those reported for easily solubilized human enzymes and other vertebrate proteins. These results suggest that the average structural gene coding such polypeptides consists of about 1400 base pairs.

Electrophoresis, Disc↗
PubMed1977

An interpretation of human diaphorase isozymes in terms of three gene loci DIA1, DIA2 and DIA3.

NADH and NADPH diaphorase isozymes have been studied in human tissues. Evidence from rare heterozygotes suggests that the red cell and main tissue forms of NADH diaphorase are products of the same locus DIA1. NADPH-dependent diaphorase appears to be the product of a second locus DIA2. A third locus, DIA3, codes for the polymorphic sperm diaphorase. The products of this locus are also found in foetal tissues including placenta and adult brain and gonads. The products of these three loci may be distinguished by their substrate specificity, thermostability and molecular size.

Adolescent↗
PubMed1976

Purification and properties of an esterase B4 from human liver.

A butyryl esterase, designated B4, has been purified from human liver and some of its properties described. The activity of this enzyme comprises 0.48% of the total butyryl esterase activity found in human liver. Esterase B4 has been distinguished from other butyryl esterases by its preference for the esters of the fluorogenic compounds 4-methyl umbilliferone and fluorescein over naphthyl esters as substrates. Other distinguishing features of this esterase include a relatively high pI (pH 8.7) A monomeric structure of low molecular weight (20 000) and high solubility in solutions of ammonium sulphate.

Amino Acids↗