Showing papers by "Morimitsu Nishikimi published in 1992"
TL;DR: Sequencing of polymerase chain reaction-amplified cDNAs for mutant and normal rat L-gulono-gamma-lactone oxidases demonstrated that the mutant cDNA has a single base mutation from G to A at nucleotide 182, which mutation alters the 61st amino acid residue from Cys to Tyr.
71 citations
01 Jan 1992
TL;DR: Comparison of the nucleotide sequences of several exons between the two species revealed that the human gene has rapidly accumulated mutations under no selective pressure once it ceased to be active, and now exists as a pseudogene in the human genome.
Abstract: Humans and other primates are lacking in L-gulono-γ-lactone oxidase, a key enzyme in the biosynthesis of L-ascorbic acid in animals, and depend on dietary intake of vitamin C to prevent scurvy. To understand the genetic basis for the enzyme deficiency as well as to produce L-ascorbic acid by genetic engineering, we isolated a cDNA clone encoding rat liver L-gulono-γ-lactone oxidase. Enzymatically active protein was expressed by transfection of monkey cells with the cDNA inserted into a eukaryotic expression vector. By use of the cDNA as a hybridization probe, L-gulono-γ-lactone oxidase genes were isolated from rat and human genomic DNA libraries in phage vectors. Comparison of the nucleotide sequences of several exons between the two species revealed that the human gene has rapidly accumulated mutations under no selective pressure once it ceased to be active, and now exists as a pseudogene in the human genome.
1 citations