William N. Valentine

-Glutamyl-cysteine synthetase deficiency. A cause of hereditary hemolytic anemia.

Abstract In some families with hemolytic anemia and a low level of reduced glutathione in erythrocytes, the disorder is associated with a deficiency of glutathione synthetase, the second of two enz...

Hereditary Hemolytic Anemia Associated with Phosphoglycerate Kinase Deficiency in Erythrocytes and Leukocytes: A Probable X-Chromosome-Linked Syndrome

Abstract A hereditary hemolytic anemia associated with a deficiency in the activity of phosphoglycerate kinase in erythrocytes and leukocytes was demonstrated in a large Chinese kindred. Two male c...

An inherited molecular lesion of erythrocyte pyruvate kinase: Identification of a kinetically aberrant isozyme associated with premature hemolysis

Atypical cases of heritable hemolytic anemia have been noted that conform clinically and biochemically to anemias of the pyruvatekinase (PK)-deficient type, except for the presence of apparently adequate quantities of erythrocyte-PK activity by the usual assay procedure. Investigations of four such anomalous cases, occurring in two unrelated families, are presented. Erythrocytes contained a kinetically aberrant isozyme of pyruvate kinase (PK(2)). Michaelis constants for the pathologic isozyme relative to phosphoenolpyruvate were over 10-fold greater than control values, but no kinetic abnormality was evident for the second substrate, adenosine diphosphate. PK(2) exhibited a pH optimum almost 1 U lower than the wild enzyme form (PK(1)). Significant differences were also evident in the functional stabilities of the isozymes. Leukocytes were unaffected. Family studies revealed paternal heterozygosity for quantitative PK deficiency of the usual type. Clinically normal maternal relatives and some siblings demonstrated intermediate deviations in erythrocyte-PK kinetics and reaction characteristics compatible with coexistence of normal PK(1) and kinetically abnormal PK(2). Hemolytic anemia in the propositi appeared to require simultaneous inheritance of the gene governing PK(2) production and its presumed allele resulting in quantitative PK deficiency. Both genetic defects were traced through three generations, the defective gene in both instances apparently resident on autosomes.A revision of the PK assay technique is suggested, since catalytic inefficiency of PK(2) was manifested only at low substrate concentrations and was therefore undetectable at the relatively high phosphoenolpyruvate levels employed in the conventional assay.

3-mercaptopyruvate sulfurtransferase (EC 2.8.1.2): A simple assay adapted to human blood cells

A product of cysteine catabolism, 3-mercaptopyruvate, is enzymatically degraded to sulfur and pyruvate by a sulfurtransferase (EC 2.8.1.2.) present in human red and white blood cells. A simple sulfurtransferase assay is reported which takes advantage of the fact that pyruvate is conveniently measured enzymatically by lactate dehydrogenase (LDH) after the elimination of 3-mercaptopyruvate, also a substrate of LDH, by addition of N-ethylmaleimide. Sulfite is employed as sulfur acceptor, and conditions for a reproducible assay including data for preparation and storage of reactants, their assay, and their optimal concentrations are given. The apparent Km for sulfite is 6.5 · 10−3 M and for 3-mercaptopyruvate is 1.9 · 10−3 M. A reducing agent, in this assay dithiothreitol (Clelands reagent), is essential for active transsulfuration. A normal metabolite, 3-mercaptopyruvate is reported elsewhere to have the capacity of producing polyploidy and chromosomal endoreduplication, a feature rendering it of interest in tumor metabolism.

Lead poisoning. Further observations on erythrocyte pyrimidine-nucleotidase deficiency and intracellular accumulation of pyrimidine nucleotides.

Pyrimidine nucleotides, detectable in normal erythrocytes only in trace quantities if at all, were found to comprise 7-80% of the intracellular nucleotide pools in nine subjects with severe lead over-burden. Blood lead concentrations ranged from approximately equal to 200- to 400-microgram/dl packed cells, and the greatest accumulations of pyrimidine-containing nucleotides occurred in the two subjects with the highest blood lead levels. Most of the patients had mild or moderate anemia and moderate basophilic stippling evident in Wrights-stained peripheral smears. Pyrimidine nucleotidase activities were inhibited to 13-28% of the mean activity in normal control erythrocytes and even more so (5-15%) when compared to specimens with increased reticulocytes and young cells. Reticulocytosis was absent in two subjects and modest to moderate in the remainder, but erythrocyte assays revealed the substantial elevations in populations of young mean cell age. Inappropriately low reticulocyttial elevations in glucose-6-phosphate dehydrogenase expected in populations of young mean cell age. Inappropriately low reticulocyte responses may reflect hematopoietic suppressive effects of lead at a variety of metabolic loci.

Occurrence of Defective Hexosephosphate Isomerization in Human Erythrocytes and Leukocytes

Abstract Deficient activity of erythrocyte and leukocyte glucosephosphate isomerase was found in three siblings with hereditary hemolytic anemia who were unrelated to the single patient previously ...

Glucose Phosphate Isomerase Deficiency as a Cause of Hydrops Fetalis

ERYTHROCYTE enzymopathies are well-recognized causes of hemolytic anemia in newborn infants, but have rarely been implicated etiologically in hydrops fetalis or immediate neonatal death. Death occu...

Enzymatic Activities and Glutathione Content of Erythrocytes in the Newborn: Comparison with Red Cells of Older Normal Subjects and those with Comparable Reticulocytosis

20 enzymatic activities and the glutathione content of newborn erythrocytes are compared (a) to normal and (b) to comparably reticulocyte-rich nonneonatal red cells. Six were very high in comparison to either control group (GSH, PGK, Enol., G-3-PD, GPI, G-6-PD). Five were very low (ACHE, RPK, GSH-Px, AK and PFK). The mean of the remainder differed from the mean of comparably reticulocyte-rich blood by less than 1 SD of the latter mean. Cord erythrocytes exhibit a characteristic metabolic pattern not explained by a young mean cell age alone.

Hereditary hemolytic anemia with triosephosphate isomerase deficiency: Studies in kindreds with coexistent sickle cell trait and erythrocyte glucose-6-phosphate dehydrogenase deficiency

HE human mature erythrocyte is metabolically underprivileged. It lacks a nucleus, deoxyribonucleic acid (DNA), ribonucleic acid (RNA), an intact Krebs’ cycle or cytochrome system and the capacity to perform oxidative phosphorylation. Its metabolic requirements, small but definite, are largely satisfied by the conversion of glucose to lactate via the EmbdenMeyerhof and hexose monophosphate oxidative shunt pathways. Reduced triphosphopyridine nucleotide (NADPH) generated in the latter is recycled to triphosphyridine nucleotide (NADP) chiefly in the process of conversion of oxidized glutathione to the reduced form by the enzyme glutathione reductase. Maintenance of glutathione in the reduced state appears important in protection against certain drug challenges and oxidative stresses. Net synthesis of high energy phosphate bonds in the form of adenosine triphosphate (ATP) is derived from glycolysis, and the Embden-Meyerhof pathway of metabolism of glucose also provides a mechanism whereby NAD is converted to NADH and cycled back

Nonspherocytic Haemolytic Anaemia with Increased Red Cell Adenine Nucleotides, Glutathione and Basophilic Stippling and Ribosephosphate Pyrophosphokinase (RPK) Deficiency: Studies on Two New Kindreds

The second and third kindreds with hereditary haemolytic anaemia characterized by marked basophilic stippling of the erythrocytes, increased red‐cell GSH and adenine nucleotides, and ribosephosphate pyrophosphokinase (RPK, PRPP synthetase) deficiency are reported. In each affected subject increased auto‐haemolysis was not corrected by glucose additives in the autohaemolysis test. Despite the clearly hereditary nature of the syndrome, a heterozygous ‘carrier’ state could not be demonstrated in any family members. While autosomal recessive transmission is likely, the genetics remain obscure. The roles of substantial RPK deficiency as either a causative factor or an epiphenomenon is likewise not firmly established.