Molecular evolution of the urate oxidase-encoding gene in hominoid primates: nonsense mutations.

Nucleotide sequences of portions of second and fifth exons of urate oxidase encoding gene (UOX) of chimpanzee, gorilla, orangutan, rhesus monkey and squirrel monkey obtained following amplification by polymerase chain reaction have been compared with corresponding sequences of human, baboon and rat UOX. Two or more nonsense mutations are found in the coding regions of this UOX gene thus far analyzed in human, chimpanzee, gorilla and orangutan, but not in the baboon, rhesus monkey and squirrel monkey. Of these nonsense mutations, the stop codon at amino acid position 33 is constant in the human and the three great apes suggesting that this may be the original mutation responsible for the inactivation of the UOX gene during hominoid evolution.

Purification of biotin-binding protein from chicken egg yolk and comparison with avidin.

A simple alternative procedure for the purification in higher yields of the biotin-binding protein from the chicken egg yolk in a ligand-free form is described. The isolated protein was homogeneous by the criteria of polyacrylamide gel electrophoresis, gel filtration chromatography, immuno-double diffusion and immuno-electrophoresis. The protein had an Mr of 72 000 +/- 2000 and was a homotetramer of subunit Mr of 18 000 +/- 1000. It bound [14C]biotin in the molar ratio of 1:4 with an association constant (Ka) of 0.58 X 10(12) M-1. The yolk biotin-binding protein and avidin exhibited qualitatively similar spectral changes on interaction with biotin and p- hydroxyazobenzoic acid, but quantitatively these changes were more pronounced with avidin. Despite the lack of gross immunological cross-reactivity between the two biotin-binders, evidence based on immunological techniques for some degree of common conformational characteristics restricted to or around the ligand-binding sites of the two proteins was adduced. The mixed subunits of the two proteins failed to form hetero-oligomers on reconstitution.

Skeletal muscle carbohydrate metabolism during short-term and prolonged in vivo electrical stimulations.

Electrical stimulations were applied to the gastrocnemius muscle of intact frog. Rana hexadactyla (Lesson) for short-term (SMS) and prolonged (PMS) periods. Short-term muscular stimulations resulted in decreased glycogenolysis and glycolysis with depleted glycogen and lactic acid contents in the muscles and increased lactic acid content in the blood. The activity levels of SDH and MDH were decreased in SMS muscles. Prolonged muscular stimulations, on the other hand, increased glycogenolysis and glycogenolysis was suggested to be due to stepped-up glycogenesis. Tissue oxidative metabolism was also correlated with regulation of activities of enzymes concerned with anaerobic pathways.