Chromosomal assignment of the human 2,3-bisphosphoglycerate mutase gene (BPGM) to region 7q34----7q22

A 1.1-kb cDNA clone for human 2,3-bisphosphoglycerate mutase (BPGM) (EC 2.7.5.4) was used to map the structural gene to metaphase chromosomes. In situ hybridization experiments localized the human BPGM gene to chromosome 7 and, more precisely, to region 7q34----7q22.

Time-course of alterations of high density lipoproteins (HDL) during thyroxine administration to hypothyroid women

Serum HDL cholesterol, apolipoproteins AI and AII and post heparin lipolytic activities (PHLA) have been measured in a group of fourteen hypothyroid women without ovarian oestrogen secretion before and during a 2-month thyroxine treatment. The more rapid and consistent observed event was a decrease in apo AI levels (164 +/- 5 vs. 149 +/- 5 mg dl-1, mean +/- SEM, P less than 0.05) correlated (r = 0.79, P less than 0.05) to a slight increment of PHLA. A slight decrease in apo AII concentration was seen only after 5 days (25 +/- 2 vs. 22 +/- 2 mg dl-1, P less than 0.05) and in HDL cholesterol only after 60 days (1.3 +/- 0.6 vs. 1.1 +/- 0.5 mmol 1-1, P less than 0.05). Apo AI, HDL2 and HDL3 cholesterol were measured in another group of seven hypothyroid postmenopausal women before and after a 2-month thyroxine treatment. We observed a decrease in HDL2 cholesterol (1.69 +/- 0.20 vs. 1.17 +/- 0.09 mmol 1-1, P less than 0.02) with no changes in HDL3 cholesterol (0.88 +/- 0.09 vs. 0.99 +/- 0.06 mmol 1-1, NS). The decrease in HDL2 cholesterol correlated (r = 0.72, P = 0.05) with that for apo AI. The differential influence of thyroxine (T4) administration on the major HDL components might reflect changes in HDL composition due to the multiple effects of thyroid hormones on lipid metabolism. It can be hypothesized that the decrease in apo AI and HDL2 cholesterol concentrations are due, at least in part, to the increase in hepatic lipase activity.

Molecular cloning and sequencing of the human erythrocyte 2,3-bisphosphoglycerate mutase cDNA: revised amino acid sequence

The human erythrocyte 2,3-bisphosphoglycerate mutase (BPGM) is a multifunctional enzyme which controls the metabolism of 2,3-diphosphoglycerate, the main allosteric effector of haemoglobin. Several cDNA banks were constructed from reticulocyte mRNA, either by conventional cloning methods in pBR322 and screening with specific mixed oligonucleotide probes, or in the expression vector lambda gt 11. The largest cDNA isolated contained 1673 bases [plus the poly(A) tail], which is slightly smaller than the size of the intact mRNA as estimated by Northern blot analysis (approximately 1800 bases). This cDNA encodes for a protein of 258 residues; the protein yielded 34 tryptic peptides which were subsequently isolated by h.p.l.c. Our nucleotide sequence data were entirely confirmed by the amino acid composition of these tryptic peptides and reveal several major differences from the published sequence; the revised amino acid sequence of human BPGM is presented. These findings represent the first step in the study of the expression and regulation of this enzyme as a specific marker of the erythroid cell line.

Cloning and sequencing of mRNAs coding for two adult alpha globin chains of the salamander Pleurodeles waltlii

A cDNA library of erythrocyte mRNAs was established from immature red blood cells of the adult amphibian, Pleurodeles waltlii (urodele; salamander). The cDNA clones corresponding to the four adult globin chains were first identified and characterized by positive selection and the cDNAs derived from the two (major and minor) alpha-globin chains sequenced. The sequences presented contain both the complete 3'-noncoding region and the coding region of both chains, with the exception of the first nine codons of the minor alpha-chain, and a portion of the 5'-noncoding region of the major chain. The amino acid sequences of the encoded alpha-globin polypeptides have been deduced and compared with those of Xenopus laevis and of man. These comparative studies suggest that the alpha-globins of Pleurodeles waltlii and Xenopus laevis may have diverged from a common ancestral gene at the time when mammalian and amphibian lines diverged, and that they then evolved separately. Duplication of the alpha-gene, which is responsible for the polypeptide heterogeneity, appears to have occurred earlier in Pleurodeles waltlii than in Xenopus laevis.

[Action of Bacillus sphaericus endopeptidases on bacterial peptidoglycans and peptidoglycan fragments]

Two endopeptidases have been characterized in Bacillus sphaericus 9602: a gamma-D-glutamyl-(L) meso-diaminopimelate endopeptidase (endopeptidase I) and a gamma-D-glutamyl-L-diaminoacid endopeptidase (endopeptidase II). They are active on the peptide moieties of some bacterial peptidoglycans. Their specificities have been studied on peptides or monomeric glycopeptides derived from peptidoglycans. Their study was attempted on dimeric and polymeric fragments of a E. coli radioactive peptidoglycan. Those compounds are specifically labelled on the meso-diaminopimelate residues and are listed below.

[Thyroid hormones and the metabolism of lipoproteins]

Variations, generally not very marked, observed in triglycerides levels during thyroid affections are the result of the action of thyroid hormones on very low density lipoprotein (VLDL) metabolism. Hepatic synthesis of VLDL is increased in hyperparathyroidism due to elevation of circulating fatty acids levels, and in hypothyroidism only in obese patients. Catabolism of VLDL is accelerated in hyperthyroidism and slowed in hypothyroidism. The variations are probably related to changes in activity of lipoprotein lipase and/or hepatic triglyceride lipase, as well as structural modifications in VLDL. Variations in cholesterolemia observed during thyroid affections result mainly from alterations in low density lipoprotein (LDL) metabolism, parallel variations occurring in apoprotein B levels. Thyroid hormones increase cholesterol synthesis, and accelerate LDL catabolism by increasing the number of apoprotein B receptor in peripheral tissues and probably by other mechanisms independent of these receptors. Significant variations in cholesterol levels carried by high density lipoproteins (HDL) are not observed during hypothyroidism, an inconstant reduction being noted in hyperthyroidism. Apoprotein A2 levels are unchanged in thyroid disorders, those of apoproteins A1 being reduced in hyperthyroidism and normal in hypothyroidism, though they diminish transiently during substitutive treatment of the latter condition.

The human alpha-globin gene. The protein products of the duplicated genes are identical

In order to determine whether any heterogeneity exists in the human alpha-globin chain, i.e. whether the products of the duplicated genes are identical, we have determined the total sequence of 14 alpha-globin chains: seven of these were abnormal, while six were normal chains from the same individuals, with one additional sample which consisted of the alpha chains from a normal control. In the individuals heterozygous for an alpha-chain abnormality, the product of a single alpha-gene could be isolated from that of the three others using the differing physicochemical properties of the mutant haemoglobins. In the special situation of a double heterozygosity for an alpha-chain abnormality, the products of the two mutated genes were separated from each other and from the mixture of the products of the two normal genes. They were then investigated independently, this approach increased the precision of our work. During the course of the present investigation, sequence determinations were mainly performed on large fragments of the chains, which were purified exclusively by gel chromatography. In this way mixtures of products of several genes could be studied, thereby overcoming the risk of losing peptides differing slightly in sequence. Such loss may often occur when using ion-exchange procedures to purify small peptides. Our results show the absence of any heterogeneity at the level of the gene products of the duplicated alpha loci. Thus the human alpha-globin chain has to be considered as homogeneous.

Electrophoretic and kinetic studies of human erythrocytes deficient in pyrimidine 5'-nucleotidase

A new case of a defect in red cell pyrimidine 5'-nucleotide (P5N) activity was found in a large family from Guadeloupe in the West Indies. The propositus presented a characteristic hemolytic anemia with red cell basophilic stippling, an increased GSH level, and a shift of the peak in absorbance of nucleotide. The enzyme activity from the deficient red cells differed from that of the normal. The P5N activity of the deficient red cells was about 14% that of normal. The electrophoretic pattern of P5N activity of the deficient red cells was distinct from that of the control in terms of its Km and of the effects of pH on its maximum activity and heat stability. The significance of such differences is discussed.

Electrophoretic characterization of pyrimidine 5'-nucleotidase of human erythrocytes and its distinction from acid phosphatase

Electrophoresis of red cell pyrimidine 5'-nucleotidase was carried out on cellulose acetate strips. One major band of activity was found in preparations from human erythrocytes. This enzyme showed a specificity for the pyrimidine nucleotides UMP and CMP. No activity was detected with AMP. Pyrimidine 5'-nucleotidase activity could be separated from that of acid phosphatase with the use of alpha-glycerophosphate. This method may be useful in the study of pyrimidine 5'-nucleotidase deficiency in red cells.