Studies on human erythrocyte inorganic pyrophosphatase

Characterization of phosphohydrolase activity in bovine spleen extracts: identification of a bis(p-nitrophenyl)phosphate-hydrolyzing activity (phosphodiesterase IV) which also acts on adenosine triphosphate

Several bovine spleen enzymes with acid pH optima, some of which hydrolyze bis(p-nitrophenyl)phosphate and therefore fit the definition of "phosphodiesterase IV," were partially separated by isoelectric focusing and ion-exchange techniques. The activities were characterized by zymogram analysis with the aid of p-nitrophenyl and 4-methylumbelliferyl phosphate and phosphonate substrates. A number of these enzymes meet the criteria for phosphodiesterase I or other phosphodiesterases. However, the predominant phosphodiesterase I hydrolyzes the bis(p-nitrophenyl)-and 4-methylumbelliferyl phosphates, p-nitrophenyl and 4-methylumbelliferyl phenylphosphonate, and ATP at the beta-gamma bond, but not p-nitrophenyl or 4-methylumbelliferyl 5'-thymidylate (the usual PDE I substrates). These properties, as well as the pH optimum, distinguish the activity from the previously described, alkaline pH optimum PDE I. A second phosphodiesterase hydrolyzes only the phenylphosphonates. Several other activities, less well described, are apparent on zymograms. None of the phosphodiesterases IV was also a phosphodiesterase II (no hydrolysis of 4-methylumbelliferyl 3'-thymidylate).

Human erythrocyte carbonic anhydrase I concentrations in dried blood spots from normal and hypothyroid neonates and children

The ELISA technique was used to assay carbonic anhydrase I (HCAI) in hemolysates prepared by the elution of dried blood samples from Guthrie cards. The ratio HCAI (mg)/hemoglobin (g) measured in blood samples eluted from Guthrie cards was not significantly different from that determined in aliquots of the same blood samples after storage as erythrocyte (RBC) lysates at -20 degrees C, provided that the dried blood was eluted within three weeks of collection. The normal neonatal mean (SD) RBC HCAI concentrations were 2.05 (1.01) and 1.82 (0.86) mg HCAI/g hemoglobin for females and males respectively. Erythrocyte HCAI concentrations gradually rose with age, approaching normal adult levels by 16 years. Blood from hypothyroid neonates and hypothyroid infants on treatment gave normal HCAI/hemoglobin ratios.

A de novo case of trisomy 10p: gene dosage studies of hexokinase, inorganic pyrophosphatase and adenosine kinase

A female infant with multiple congenital anomalies is presented. Cytogenetic study revealed the presence of a de novo, supernumerary, small telocentric chromosome exhibiting the banding pattern of the short arm of chromosome no. 10 [47,XX,+10p(pter----cen)]. Her clinical features were compatible with the 10p trisomy syndrome. Hexokinase (HK-1) activity was elevated in the patient's erythrocytes, which is consistent with an assignment of HK-1 to 10pter---cen10. The absence of a gene dosage effect for inorganic pyrophosphatase (PP) in this study indicates exclusion of PP from 10pter ----cen10, and therefore implies a regional assignment of cen10----10q24 for PP. Adenosine kinase (ADK) activity was within control limits, which is consistent with exclusion of ADK from 10pter----cen10.

The synthesis of 4-methylumbelliferyl phenylphosphonate and its used in an improved method for the zymogram analysis of phosphodiesterase I

The 4-methylumbelliferyl analog of p-nitrophenyl phenylphosphonate was prepared and its cleavage by different phosphohydrolases was studied. The new compound, 4-methylumbelliferyl phenylphosphonate, is hydrolyzed by purified phosphodiesterase I (EC 3.1.4.1) from snake venom or bovine intestinal mucosa. This fact has been exploited to develop a zymogram method which allows the detection of these phosphohydrolases on gels, even when the enzymes are present in small amounts in crude extracts. This method is superior to chromogenic methods evolving p-nitrophenol in that it is far more sensitive and is superior to the 4-methylumbelliferyl thymidine 5'-phosphate method in that the substrate is easier to prepare and can be isolated in large quantity.

Chromosome localization of the loci GOT1, PP, NP, SOD1, PEPA and PEPC in the American mink (Mustela vison)

Twenty eight American mink × Chinese hamster somatic cell hybrids were analysed for the expression of mink enzymes and chromosome segregation. This analysis made it possible to assign the genes for glutamate-oxaloacetate transaminase-1 (soluble) (EC 2.6.1.1), inorganic pyrophosphatase (EC 3.6.1.1), purine nucleoside phosphorylase (EC 2.4.2.1) to mink chromosome 2, superoxide dismutase-1 (soluble) (EC 1.11.1.1) to chromosome 5, peptidase A (EC 3.4.11 or 3.4.13) to chromosome 4, and peptidase C (EC 3.4.11 or 3.4.13) to chromosome 13. It is suggested that the synthenic gene group GOT1-PP-NP is located on the short arm of mink chromosome 2.

Visualization of isozymes which generate inorganic phosphate

A sensitive, new enzymatic method for the detection of isozymes which liberate inorganic phosphate (or pyrophosphate) is described. The new method for the detection of phosphate differs from the established method for nucleoside phosphorylase by the substitution of one reagent. The new enzymatic method, compared to existing methods for the detection of phosphate on electrophoretic gels, is advantageous due to its sensitivity and generation of a nondiffusible formazan chromogenic product.

A survey on the formation and localization of secondary isozymes in mammalia

A survey on the formation of secondary isozymes (= multiple molecular forms of enzymes) is given by means of well-documented enzyme systems. Further examples of a certain type of formation are summarized in tabular form. Eight different classes of enzyme variants deriving from translational processes are discussed. These are: aggregation, polymerization, oxidation and reduction of free SH groups, limited proteolysis, cleavage of carbohydrate residues, deamidation, noncovalent binding of coenzymes, and conformational isomerism. In addition, the intracellular distribution of secondary isozymes is discussed, as are the formation of artificial enzyme variants and the recognition of multiple enzyme forms caused by an exchange of neutral amino acids. About 200 original papers are cited. The reference list was completed in early 1979.

Genetic studies on the Ticuna, an enigmatic tribe of Central Amazonas

The Ticuna are an Amerindian tribe of Central Amazonas, a key location in theories of the peopling of eastern South America. The results of typing some 1760 members of the tribe with respect to 37 different genetic systems are reported, as are the results of HLA typings on a subsample of 129 persons. Salient findings include the following. (1) Except for a high frequency of LMs allele and an unusual combination of HLA allele frequencies, there are no notable findings with respect to the commonly studied polymorphic systems. A multivariate treatment of six of the most commonly studied genetic polymorphisms accords the Ticuna an 'average' position among Amerindian tribes. (2) There is much less intervillage heterogenicity than usually encountered in Amerindian tribes; this is attributed to recent high rates of intervillage migration due to religious developments. (3) A thus-far unique polymorphism of ACP1 was identified, the responsible allele having a frequency of 0.111. (4) In proportion to the size of the tribe, there was a relative paucity of 'private' genetic variants, the ACP1 allele being the only one. This discrepancy is attributed to a relatively recent numerical expansion of the tribe; effective population size over the past several thousand years is thought to have been well below what present numbers would suggest. (5) The thesis is again advanced that 'private variants' (alleles not occurring as polymorphisms of wide distribution) are more common in Amerindian than in Caucasian or Japanese populations.

Relationship between subunit size and number of rare electrophoretic alleles in human enzymes

Data from published sources were used to compare the numbers of different electrophoretic alleles of 29 monomeric and dimeric human enzymes to their respective subunit molecular weights. Only those human enzymes were considered for which the total sample sizes were in excess of 2000 individuals. Correlations between these two variables were determined within sample size ranges of 2000 less than or equal to n less than or equal to 3000 and 4000 less than or equal to n less than or equal to 5000 individuals, and separately by quaternary class. There was no statistically significant correlation observed for the smaller sample size range in monomers; however, the correlations for the larger sample size range in monomers and both ranges in dimers were significant. Since there is no relationship between subunit size and heterozygosity, the relationships are due primarily to the incidence of rare alleles. These findings demonstrate the effect of locus-specific mutation rates, expected as a consequence of variation of cistron sizes, and imply that other forces are responsible for the relative frequencies of common alleles at some of the loci.

Malate dehydrogenase types in the Asian-Pacific area, and a description of new phenotypes

A survey of more than 21 000 haemolysates from blood samples collected in various parts of south and southeast Asia, Australasia and the Western Pacific and examined in this laboratory has revealed several new alleles controlling variants of sMDH; in addition, further information has been provided on the distribution of sMDH3 in New Guinea. Two of the variant alleles, sMDH3 and sMDH6, achieve polymorphic frequency in various populations. sMDH3 is widely distributed in New Guinea, with highest frequencies in the Eastern Highlands. The pattern of its distribution suggests the mutant arose originally in a Papuan-speaking population. So far, sMDH6 has been detected only in Micronesians from a number of islands in the Carolines. A single example of another new variant, sMDH 5-1, and two examples of a slow variant, sMDH 7-1, were detected in samples from Iran and Singapore, respectively. No examples of mMDH variants were found in a total of 652 placental extracts from Papua New Guinea and Australia.

The status of the gene map of the human chromosomes

In man, the specific chromosome that carries each of about 210 gene loci is known. These loci include at least one assigned to each chromosome (including the Y), about 110 assigned to specific autosomes, and about 100 to the X chromosome. For many loci, information on regional chromosomal localization is also available. The information comes mainly from studies in families and somatic cell hybrids, as well as an intgratsight of results from the two methods. Knowledge of the chromosome map gives insight into evolution, chromosomal organization in relation to genetic control mechanisms, and the pathogenesis of neoplasms and malformations. Furthermore, it is useful in prenatal or premorbid diagnosis of hereditary diseases.

An investigation of some factors affecting levels of erythrocyte inorganic pyrophosphatase activity

A reproducible method has been devised for assaying erythrocyte inorganic pyrophosphatase. The activity level in healthy individuals appears to be a constant characteristic. Population surveys have been carried out in 100 Europeans and 34 Indians. In each population an otherwise normal individual was found with activity approximately three standard deviations from the mean. Investigation of the family of one such individual indicated that this was an inherited characteristic. A few individuals with clinical abnormalities were examined and some were found to have activity levels above the normal range. High activity levels appeared to be associated with those diseases in which raised circulating reticulocyte levels are found. The rate of in vivo decay of erythrocyte inorganice pyrophosphatase has been measured in healthy individuals. The decay pattern appears to be of the constant logarithmic type. An estimate has been made of the activity in circulating reticulocytes, and the half life of the enzymes has been calculated.

Phosphoglucomutase types in the Asian-Pacific area: a critical reveiw including new phenotypes

The distribution of genetic variants at the PGM1 and PGM2 loci in South and East Asia, the Western Pacific and Australasia has been surveyed on the basis of published and unpublished material comprising samples from some 33,000 persons. A critical comparsion of previously described and of new rare alleles at both loci has been undertaken. The present number for PGM1 is 14 and for PGM2 is 12. Many of these have restricted geographic or ethnic distribution.