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Biomedical subjects

G K Smith

Publications and source records attributed to G K Smith.

At least 109 records · Page 6Linked to original sources
PubMed1980

Characterization of the enzyme complex involving the folate-requiring enzymes of de novo purine biosynthesis.

Evidence is presented for a functional association of GAR TFase and the trifunctional protein within the protein complex consisting of GAR TFase, AICAR TFase, Ser HMase, and trifunctional protein. Resolution of the trifunctional protein from the remaining enzymes in the complex causes a loss of GAR TFase activity which is regained upon recombination. The minimum stoichiometry for GAR TFase reactivation is 3:1 GAR TFase--trifunctional protein. Determination by ultracentrifugation of the sedimentation coefficient as a function of protein concentration disclosed that the complex is in mobile equilibrium with the individual proteins. However, mixed GAR TFase--trifunctional protein species can be detected by trapping with cleavable bifunctional cross-linking reagents. Additional support for their interaction is found in the kinetic coupling of the trifunctional protein and GAR TFase activities that leads to a fourfold more efficient formation of formylglycinamide ribotide commencing with formate rather than with 5,10-methenyl-H4folate triglutamate.

Acyltransferases↗
PubMed1978

Glutathione-facilitated refolding of reduced, denatured bovine seminal ribonuclease: kinetics and characterization of products.

Totally reduced and denatured seminal ribonuclease was regenerated using the glutathione redox system. The refolding kinetics of the enzyme were determined as a function of redox state, temperature from 14 to 43 degrees C, pH, and protein concentration. The maximal rate of regeneration occurred with 3 x 10(-3) M reduced glutathione, 6 x 10(-4) M oxidized glutathione, 24 to 30 degrees C, and pH 8.2. The products of the refolding process were characterized by Sephadex G-75, sodium dodecyl sulfate gel electrophoresis, enzymatic activity, circular dichroism, and amino acid analysis. The results indicate that the native dimeric form of the enzyme is not produced during refolding to any appreciable extent; rather, the major product is monomeric. The purified monomer exhibits twice the activity of the native enzyme toward yeast RNA. Its circular dichroism spectrum is different from the native enzyme and is quite similar to that of pancreatic ribonuclease A. Amino acid analyses showed that two glutathione molecules are bound to the monomer, suggesting that cysteine-31 and -32, which normally form the intermolecular disulfide bonds, are blocked.

Amino Acids↗
PubMed1978

Fetal and placental growth in the rat following differential reduction of litter size.

The effects on fetal and placental growth of differential litter size reduction on day 10 (LR10) and day 13 (LR13) were determined in the rat. LR10 resulted in significant increments in placental weight, fetal body and brain weight, and brain protein content in the survivors at day 21. A marginal effect on brain cellularity (DNA) was observed. Values for these parameters generally followed the extent of reduction. Placenta weight was also related to original litter size. In contrast, LR13 which was associated with survival of supernumerary placentae (those without a fetus) produced no growth enhancement. Prenatal development was discussed in terms of general systemic influences and hormonal regulatory mechanisms.

Animals↗
PubMed1975

Prolongation of gestation by growth hormone: a confounding factor in the assessment of its prenatal action.

The administration of urified growth hormone to normally nourished pregnant rats prolonged gestation leading to postmaturity of the offspring. The effect explains, in part, the apparent influence of growth hormone on prenatal and early postnatal development and supports the notion that the prenatal action of exogeneous growth hormone is restricted to a therapeutic one under conditions of malnutrition.

Animals↗
PubMed1973

Selection for treatment in spina bifida cystica.

This paper discusses (1) the mortality in 295 patients with myelomeningocele born 1961-9, (2) the "quality of life" of 88 surviving patients born 1961-5, and (3) their implications for selection for treatment in spina bifida cystica. Evidence is presented that high neurological levels, the presence of severe hydrocephalus, especially if present at birth, meningitis and ventriculitis, and gross renal disease are very adverse factors both in mortality and in quality of life. In selection for treatment we recommend immediate repair of the sac in most low lesions, deferring treatment in high lesions, and re-evaluation of the survivors of the latter group at 1 month or later.

Age Factors↗