The cDNA cloning and molecular evolution of reptile and pigeon lactate dehydrogenase isozymes

The cDNAs encoding lactate dehydrogenase isozymes LDH-A (muscle) and LDH-B (heart) from alligator and turtle and LDH-A, LDH-B, and LDH-C (testis) from pigeon were cloned and sequenced. The evolutionary relationships among vertebrate LDH isozymes were analyzed. Contrary to the traditional belief that the turtle lineage branched off before the divergence between the lizard/alligator and bird lineages, the turtle lineage was found to be clustered with either the alligator lineage or the alligator-bird clade, while the lizard lineage was found to have branched off before the divergence between the alligator/turtle and bird lineages. The pigeon testicular LDH-C isozyme was evidently duplicated from LDH-B (heart), so it is not orthologous to the mammalian testicular LDH-C isozymes.      

Effect of various alkyl and unsaturated substituents on the mutagenicity of some nitrophenyl thioethers.

A variety of nitro-substituted phenyl alkyl/aryl thioethers and nitroso-substituted phenyl alkyl/aryl thioethers have been synthesized and tested for their mutagenicity towards Salmonella typhimurium strain TA100, TA98, TA98NR and TA98/1,8-DNP(6) in the absence of S9 mix. The relative order of mutagenicity in TA98 and TA100 among p-nitrophenyl thioethers having alkyl or aryl substituents is allyl>phenyl>benzyl>butyl>propyl>ethyl>methyl. Compounds having an alkyl chain C(6) to C(12) were found to be non-mutagenic. Among the various positional isomers (ortho, meta and para) of nitro-substituted diphenyl thioethers only the compounds having the -NO(2) function at the para position is mutagenic, whereas compounds having a -NO(2) function at ortho and meta are non-mutagenic. However, the reduced intermediate, ortho-nitroso derivative was found to be mutagenic in all the four strains but the meta-nitroso derivative was found to be non-mutagenic. All mutagens were found to be non-mutagenic when tested in nitroreductase deficient strain TA98NR, whereas their nitroso intermediates are found to be mutagenic. A substantial fall in the mutagenic activity is observed when some mutagens are tested in O-acetyltransferase deficient strain TA98/1,8-DNP(6).     

Enzymatic synthesis of a sialyl Lewis X dimer from egg yolk as an inhibitor of E-selectin

A dimeric sialyl Lewis X (SLe^x) glycopeptide was synthesized enzymatically in three steps from an N-linked oligosaccharide prepared from egg yolk. Treatment of delipidated hen egg yolk with the protease Orientase and neuraminidase gave a dimeric N-acetyllactosamine-containing oligosaccharide linked to asparagine. Addition of sialic acid and fucose catalyzed by -2,3-sialyltransferase and -1,3-fucosyltransferase provided the dimeric SLe^x, which was shown to be as active as monomeric SLe^x as an inhibitor of E-selectin with IC₅₀ 0.75 mM. The synthetic dimeric SLe^x of the mucin type (i.e. SLe^x linked to the 3- and 6-OH groups of Gal) is, however, about five times as active as the monomer. It is suggested that dimeric SLe^x glycopeptides of the mucin type would be effective ligands for E-selectin.     

Plasma alpha 1B-glycoprotein allele frequencies in Finns and Swedish Lapps: evidence for a new alpha 1B allele

A new allele (A1B*5) of human plasma alpha 1B-glycoprotein (alpha 1B) was reported. alpha 1B phenotyping was done by two-dimensional agarose gel (pH 5.4)-horizontal polyacrylamide gel (pH 9.0) electrophoresis followed by protein staining. The alpha 1B phenotypes 1-1, 1-2, 1-5 and 2-2 were observed in Finns and phenotypes 1-1, 1-2, 1-5 and 2-5 in Swedish Lapps. The respective frequencies of A1B*1, A1B*2 and A1B*5 were 0.9575, 0.0350, 0.0075 in Finns and 0.8922, 0.0653, 0.0425 in Swedish Lapps. The Swedish Lapps showed a higher degree of alpha 1B polymorphism (polymorphism information content = 0.19) than other Caucasian populations that have been studied.