Characteristics of enzymes of erythrocytes from newborn infants and adults: Activity, thermostability, and electrophoretic profile as a function of cell age

Mohrenweiser, Harvey W.; Fielek, S; Wurzinger, K. H.

doi:10.1002/ajh.2830110203

Cited by 41 publications

(27 citation statements)

References 29 publications

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“…The levels of enzyme activity and the cord blood to the adult blood activity ratios were similar to those in previous reports (10,13). The higher enzymatic activities in umbilical cord blood samples, for all enzymes except adenylate kinase, generally reflect differences in mean red cell age and percentage of reticulocyte between adult and cord blood samples, although they may also reflect unique characteristics of fetal erythrocytes (e.g., GPI), (14)(15)(16).…”

Section: Resultsmentioning

confidence: 99%

“…DISCUSSION Abnormal enzyme activities in erythrocytes may be due to several causes in addition to a structural alteration involving a single enzyme locus. Most ofthese causes, including changes in mean cell age or cell type (15,16), exposure to cytostatic drugs (22), and other dyserythropoietic conditions (23,24) usually result in alterations in the activity of several enzymes simultaneously and usually involve both increases and decreases in activity. Therefore, it is unlikely that an acquired enzymopathy would fulfill our requirement that the level of enzymatic activity for eight of the nine enzymes assayed be within the normal range (excluding the G6PDA-variant).…”

Section: Resultsmentioning

confidence: 99%

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Frequency of enzyme deficiency variants in erythrocytes of newborn infants.

Mohrenweiser¹

1981

Proc. Natl. Acad. Sci. U.S.A.

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The frequency of enzyme deficiency variants, defined as alleles whose products are either absent or almost devoid of normal activity in erythrocytes, was determined for nine erythrocyte enzymes in some 675 newborn infants and in approximately 200 adults. Examples of this type of genetic abnormality, which in the homozygous condition are often associated with significant health consequences, were detected for seven of the nine enzymes studied. Fifteen inherited enzyme deficiency variants in 6142 determinations from the newborn population and 5 variants in 1809 determinations from adults were identified. Seven of the deficiency variants involved triosephosphate isomerase, a frequency of0.01 in the newborn population. The average frequency of 2.4/1000 is 2-3 times the frequency observed for rare electrophoretic variants of erythrocyte enzymes in this same population.Recent years have witnessed a great wave ofenthusiasm for the electrophoretic approach as a means of defining the frequency of "occult" variation in a random sample of a plant or animal population. Strong tool though this has been, it has been recognized that this technique reveals only the tip of the iceberg, in that it fails to detect variants not associated with a charge change in the molecule under scrutiny, and it usually fails to detect variation characterized by actual or functional loss ofgene product. In this paper we will describe the results of an effort to determine the frequency ofgenetic variants resulting in total or near-total loss of activity for a series of nine human erythrocyte enzymes. We have previously reported on the frequency of rare electrophoretic variants in this sample, and in a companion paper (1) we will report the results of studies designed to estimate, for the same population and enzymes, the frequency of genetic variants exhibiting alterations in thermostability. Both investigations were undertaken in the context ofan effort to move the study of human mutation rates to the biochemical level (2).In 1932, Muller (3), in an attempt to classify types of genetic variation, distinguished between amorphs, hypomorphs, and hypermorphs. An amorph was a variant in which gene product (as then understood) was totally absent. In retrospect, Garrod in 1909 (4) defined the first amorph in man. Currently, over 100 metabolic diseases have been described in which a specific enzyme defect, either an amorph or a hypomorph in the terminology of Muller, has been identified (5-7). Almost all of these defects are detectable in the heterozygote or "carrier" individual through a significant reduction in enzyme activity, usually approaching 50% of the expected value (6). Although we have been unable to trace the origin of the term, these deficiences and in particular the amorphs, are often called "nulls."Our knowledge of the population frequency of null alleles in humans has been largely indirect, in the sense that most estimates take as their point of departure a recessively inherited disease characterized by loss of enzyme activity, fo...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Frequency of enzyme deficiency variants in erythrocytes of newborn infants.

Mohrenweiser¹

1981

Proc. Natl. Acad. Sci. U.S.A.

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“…Homozygous-deficient individuals usually have 3-20% of normal TPI activity; all of this activity is heat labile, suggesting that at least one allele encodes a structurally altered protein (3, 9, 10). The other allele is presumably null, since mutations producing no detectable enzyme activity or immunologically cross-reacting material are by far the most prevalent abnormality affecting the human TPI locus (11)(12)(13)(14)(15).In the present study, we have determined the nucleotide sequence of two TPI alleles, each of which was isolated from unrelated individuals homozygous for TPI deficiency. Relative to a normal allele (16), each allele harbors a single base pair change.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Human triose-phosphate isomerase deficiency: a single amino acid substitution results in a thermolabile enzyme.

Daar¹,

Artymiuk²,

Phillips³

et al. 1986

Proc. Natl. Acad. Sci. U.S.A.

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Triose-phosphate isomerase (TPI; D-glyceraldehyde-3-phosphate ketol-isomerase, EC 5.3.1.1) deficiency is a recessive disorder that results in hemolytic anemia and neuromuscular dysfunction. To determine the molecular basis of this disorder, a TPI allele from two unrelated patients homozygous for TPI deficiency was compared with an allele from a normal individual. Each disease-associated sequence harbors a G-C -+ C-G transversion in the codon for amino acid-104 and specifies a structurally altered protein in which a glutamate residue is replaced by an aspartate residue. The importance of glutamate-104 to enzyme structure and function is implicated by its conservation in the TPI protein of all species that have been characterized to date. The glutamate-toaspartate substitution results in a thermolabile enzyme as demonstrated by assaysof-TPI activity in cultured fibroblasts of each patient and cultured Chinese hamster ovary (CHO) cells that were stably transformed with the mutant alleles. Although this substitution conserves the overall charge of amino acid-104, the x-ray crystal structure of chicken TPI indicates that the loss of a side-chain methylene group (-CH2CH2COO -* -CH2COO ) is sufficient to disrupt the counterbalancing of charges that normally exists within a hydrophobic pocket of the native enzyme.Triose-phosphate isomerase (TPI; D-glyceraldehyde-3-phosphate ketol-isomerase, EC 5.3.1.1) catalyzes the movement of a single proton to interconvert dihydroxyacetone phosphate and glyceraldehyde 3-phosphate in glycolysis and gluconeogenesis (1). The enzyme, a dimer of identical subunits that are 248 amino acids in humans (2, 3), has no cofactors, required metal ions, or cooperativity between subunits. Both prokaryotic and eukaryotic TPI are very similar in sequence and structure and are characterized by a high catalytic efficiency. The second-order rate constant for the formation of dihydroxyacetone phosphate, the thermodynamically favored reaction, is close to the rate constant for a diffusion-limited encounter of substrate and enzyme (4, 5).Site-directed mutagenesis combined with crystallographic and kinetic studies have provided a means of defining the contribution of specific TPI amino acids to enzyme activity (6, 7). This method has focused on amino acids implicated by high-resolution structural data and chemical-modification experiments to be important to the catalytic mechanism of the enzyme. We have chosen a complementary approach to understand TPI structure-function relationships in studying natural TPI gene mutations that exist within the human population. Hereditary TPI deficiency is an autosomal recessive disease that has severe clinical manifestations including chronic hemolytic anemia and neuromuscular disorders (8). Homozygous-deficient individuals usually have 3-20% of normal TPI activity; all of this activity is heat labile, suggesting that at least one allele encodes a structurally altered protein (3, 9, 10). The other allele is presumably null, since mutations producing no detectable ...

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“…Wurzinger and Mohrenweiser (1982) reported that cord blood erythrocyte GOT1 activity was 1.3 times the activity in erythrocyte from pregnant females, 1.5 times the activity in non-pregnant females and 2.0 times the activity in males. The cord blood-adult blood disparities were thought to be related to cell age (Sass et al, 1964;Gahr et al, 1979;Mohrenweiser et al, 1981), while those between pregnant females and normal adults were related to increased vitamin B6 (pyridoxine) intake Jpn. Jo Human Genet.…”

Section: Resultsmentioning

confidence: 99%

Electrophoretic variants of blood proteins in Japanese VII. Cytoplasmic glutamate-oxaloacetate transaminase (GOT1)

Satoh

Takahashi

et al. 1986

Jap J Human Genet

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SummaryA total of 16,835 children, of whom 11,737 are unrelated, from Hiroshima and Nagasaki were examined for erythrocyte cytoplasmic glutamate-oxaloacetate transaminase (GOT1) by starch gel electrophoresis. A variant allele named GOTI*2HR1 which seems to be identical with GOT1*2 was encountered in polymorphic frequency. Five kinds of rare variants, 3NG1, 4NG1, 5NG1, 6HR1 and 7NG1 were encountered in a total of 109 children. Except for 7NGI for which complete family study was unable, family studies confirmed the genetic nature of these rare variants, since for all instances in which both parents could be examined, one of the parents exhibited the same variant as that of their child. Thermostability profiles of these six variants were normal. The enzyme activities of five were decreased, while the value of one was normal compared to that of GOTI 1.

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Characteristics of enzymes of erythrocytes from newborn infants and adults: Activity, thermostability, and electrophoretic profile as a function of cell age

Cited by 41 publications

References 29 publications

Frequency of enzyme deficiency variants in erythrocytes of newborn infants.

Frequency of enzyme deficiency variants in erythrocytes of newborn infants.

Human triose-phosphate isomerase deficiency: a single amino acid substitution results in a thermolabile enzyme.

Electrophoretic variants of blood proteins in Japanese VII. Cytoplasmic glutamate-oxaloacetate transaminase (GOT1)

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