Search PubMed⌕ Search

Biomedical subjects

A Yoshida

Publications and source records attributed to A Yoshida.

At least 1,171 records · Page 65Linked to original sources
PubMed1980

Structure and function of normal and variant human phosphoglycerate kinase.

Complete amino acid sequence of normal human phosphoglycerate kinase (PGK) was determined. The enzyme consists of 417 amino acid residues with acetylserine at the NH2-terminal and isoleucine at the COOH-terminal. The structural abnormality of PGK-II, which is fairly common in Southern Pacific populations, is a single amino acid substitution from threonine in the normal enzyme to asparagine in the variant enzyme at the 352nd position. The substitution induced no change in the enzyme activity, but induced strong binding of the variant enzyme with citrate. The structural abnormality of PGK-München is a single amino acid substitution from aspartic acid in the normal enzyme to asparagine in the variant enzyme at the 267th position. PGK-München is associated with red cell enzyme deficiency (about 20% of normal), and substantial heat instability. Therefore, the negative charge of an aspartyl residue at the 267th position must play a role in maintaining the stability of the enzyme molecule. Possible mechanisms of hemolysis due to hereditary deficiency of PGK are discussed.

Amino Acid Sequence↗
PubMed1980

A contradiction between in vivo and in vitro activities of normal and variant glucose 6-phosphate dehydrogenase.

The presumed "physiologic activity" of normal glucose 6-phosphate dehydrogenase (G6PD), i.e. activity assayed in the presence of physiologic concentrations of ATP, 2,3-diphosphoglycerate, glucose 6-phosphate, NADP and NADPH in the normal red cells, is comparable to shunt pathway activity of intact normal red cells. In contrast, the presumed "physiologic activity" of G6PD variants associated with enzyme deficiency (Gd A- and Gd Mediterranean) is one order of magnitude higher than actual shunt pathway activity of the variant red cells. The difference of kinetic parameters of the enzyme in artificial buffer media and presumed physiologic medium in red cells cannot explain the discrepancy. The apparent discrepancy could be attributed either to (a) over-estimation of NADP and under-estimation of NADPH concentrations in the G6PD deficient red cells due to rapid oxidation of NADPH to NADP in preparation of hemolysate, or to (b) a large portion of NADP which accumulated in the G6PD deficient red cells binds with cellular components of intact red cells and is not available as substrate for G6PD.

Erythrocytes↗
PubMed1980

Effects of amino acid imbalance on polysome profiles and 14C-labeled amino acid incorporation into tissue proteins in rats.

Feeding of rats on a low casein diet supplemented with a small amount of methionine caused an enlargement of liver size and an accumulation of lipids in the liver. Experiments were conducted to examine the effects induced by the amino acid-imbalanced diet on the metabolism of dietary amino acids with special reference to protein synthesis. Protein and DNA contents of the liver per 100 g body weight with rats fed on the imbalanced diet were apparently higher than those of rats fed on the basal diet. Ingestion of the imbalanced diet clearly stimulated hepatic ribosome aggregation but not skeletal muscle ribosome aggregation. Incorporation of [14C]leucine into liver protein was markedly increased in the group consisting of rats fed on the imbalanced diet (imbalanced group) and that into skeletal muscle was similar to the result with the group receiving the basal diet (basal group). Relative content of [14C]leucine in plasma albumin was higher in rats of the imbalanced group, whereas that in plasma of very low-density lipoprotein was reduced. These results indicate that the unbalanced inter-organ or intra-organ utilizations of dietary amino acids for protein synthesis were produced by the condition of the amino acid imbalance. Such metabolic effects of the amino acid imbalance may result in the enlargement of liver size and the accumulation of lipids in the liver.

Amino Acids↗
PubMed1980

Plasma blood group glycosyltransferase activities after bone marrow transplantation.

Human blood groups (ABO) are known to be determined by the terminal glycosyl residues attached to common carbohydrate chains of the red cell surface. N-acetylgalactosaminyltransferase (A-enzyme) in blood group A persons and galactosyltransferase (B-enzyme) in blood group B persons are responsible for producing A and B substances on the red cell surface, with both enzymes absent in blood group O persons. The plasma transferase (A - and B-) activity was assayed after the complete replacement of the bone marrow of patients with acute leukemia or aplastic anemia by transplantation bone marrow from donors with ABO blood group differing from the recipient. The patient's blood type completely changed from the recipient's type to the donor's type. However, the A- and B-enzyme activities of the patients changed only slightly after bone marrow transplantation. The results indicate that most of the A- and B-enzymes in the circulatory plasma is not derived from the bone marrow, lymphoid, or macrophage tissue. Other tissues must be the primary source of the enzymes in plasma.

ABO Blood-Group System↗
PubMed1980

Genetic mechanism of cis-AB inheritance. I. A case associated with unequal chromosomal crossing over.

In contradiction to the general Mendelian inheritance of blood group ABO expression, the A and B characteristics are inherited together from one parent in the rare Cis-AB phenotype. Since the synthesis of blood group A and B substances are controlled by N-acetylgalactosoaminyltransferase (A-enzyme) and galactosyltransferase (B-enzyme), the genetic mechanism of Cis-AB expression may be elucidated by examining the characteristics of A- and B-enzymes in Cis-AB plasma. Biochemical study reveals that the examined Cis-AB plasma contains two separable enzyme components: one with kinetic properties similar to those of common A2-enzyme, but differing from A1-enzyme, and another with kinetic characteristics similar to those of common B-enzyme. Therefore, Cis-AB expression, at least in the case examined, is due to unequal crossing over, producing a chromosome with alleles for A2- and B-enzymes, rather than to a structural mutation in A or B alleles producing a single abnormal enzyme with bifunctional activity.

ABO Blood-Group System↗
PubMed1980

Genetic mechanism of Cis-AB inheritance. II. Cases associated with structural mutation of blood group glycosyltransferase.

The genetic mechanism of the rare occurrence of Cis-AB expression, that is, AB and/or O offspring from AB X O parents, has not been fully understood. The synthesis of blood group A and B substances are controlled by N-acetylgalactosaminyltransferase (A-enzyme) and galactosyltransferase (B-enzyme). Therefore, the genetic mechanism of Cis-AB expression may be elucidated by examining the characteristics of A- and B-enzymes in Cis-AB plasma. In a previous study, we presented evidence that Cis-AB expression in one case examined was due to unequal chromosomal crossing over producing a single chromosome with the genes for A. and B-enzymes, rather than to a structural mutation producing a single abnormal enzyme with bifunctional activity. In contrast to the previous case, the present two Cis-AB plasma contained a single abnormal enzyme that can transfer both N-acetylgalactosamine (GalNAc) and galactose (Gal). Moreover, the subjects' plasma also contained an enzymatically inactive, but immunologically cross-reacting material. Therefore, Cis-AB expression in the present two cases is due to a structural mutation in either the A or B gene producing a single abnormal enzyme with bifunctional activity.

ABO Blood-Group System↗