Conformational analysis of cyclolinopeptide A, a cyclic nonapeptide: nuclear Overhauser effect and energy minimization studies.

The conformation of cyclolinopeptide A [cyclo(Pro-Pro-Phe-Phe-Leu-Ile-Ile-Leu-Val)], a naturally occurring cyclic nonapeptide has been investigated in dimethylsulfoxide solution by 270 MHz 1H-nmr. A complete assignment of all C alpha H and NH resonances has been accomplished using two-dimensional correlated spectroscopy and nuclear Overhauser effects (NOEs). Analysis of interresidue NOEs and JHNC alpha H values permit construction of a molecular model for the cyclic peptide backbone.

Interaction of alcohol and protein deficiency on rat brain synaptosomal (Na+-K+)-ATPase.

Administration of low amounts of ethanol for a prolonged period increases rat brain synaptosomal (Na+-K+)-ATPase activity, the increase being less in the protein deficient rats. The adaptive mechanism to offset the stress imposed by the continued presence of ethanol seems to be depressed by low plane of nutrition. In vivo and in vitro effects of ethanol on (Na+-K+)ATPase seems to be different.

Effect of maternal alcohol consumption on the lipid composition of CNS in the offspring.

Maternal alcohol consumption at a level that does not affect calorie intake increases cholesterol concentration and content as well as incorporation of labeled glucose into cholesterol in the brain and spinal cord of newborn rat pups. Continued consumption of alcohol during lactation also affects the galactolipid concentration in the brain and spinal cord of pups at 21 days of age, and this increase seems mainly to be due to an increase in content of myelin lipids. Analysis of myelin shows that the concentration of phospholipids also increases in this fraction.

Nuclear Overhauser effects as probes of peptide structure. A diagnostic for left-handed helical conformations.

The conformational dependence of the interresidue interproton distances in peptides, C alpha H ...

A novel supersecondary structure in globular proteins comprising the collagen-like helix and beta-turn.

A structure consisting of the polyproline-II or collagen-like helix immediately succeeded by a beta-turn is seen in several synthetic peptides and has been suggested to be the conformational requirement for proline hydroxylation in nascent procollagen. Using a simple algorithm for detecting secondary structures, we have analysed crystal structure data on 40 globular proteins and have found eight examples of the collagen-helix + beta-turn supersecondary structure in 15 proteins that contain the collagen-like helical segments.

Conformation of glycyl residues in globular proteins.

Glycine is unique among the amino acids in view of its symmetric nature. While the overall distribution of glycyl residues in the (phi, psi) plane is near-symmetric, there can be certain preferences for the individual conformations. An analysis of the observed glycyl conformations in 70 proteins has been carried out to find the influence of residues adjoining the glycyl residues.

Role of microorganisms in improving nutritional status of the poor.

The intestinal microflora as well as bacteria involved in fermentation of foods ordinarily consumed in India may contribute substantially for the improvement of nutritional status of poor Indians.

Effects of pre-weaning undernutrition and post-weaning rehabilitation on polyphosphoinositide pools in rat brain regions.

In order to assess the effects of undernutrition during the pre-weaning period on polyphosphoinositide (PolyPI) pools in rat cerebral cortex, brain stem, and cerebellum, dams were fed 5% (L-) or 22% (L+) protein diets from birth to weaning and the pups were used at this age for analyses. To examine rehabilitation post-weaning, L- and L+ pups were fed 22% protein diets (P+) for an additional six week period. Rats were decapitated and the dissection begun either immediately ("0 min" samples) or 10 min later (10 min samples).

Developmental pattern of alkaline phosphatase in soluble and particulate fractions of rat skull cap and femur.

Alkaline phosphatase is detected in both soluble and particulate fractions of rat bone. The concentration of alkaline phosphatase in the particulate fraction of rat skull cap bone and femur is high during the peak period of calcification of these bones suggesting the possibility of using it as a marker for the rate of bone calcification.

Effects of neonatal undernutrition and subsequent nutritional rehabilitation or administration of thyroxine and hydrocortisone on the inositol phosphatase activities in rat intestine.

Undernutrition during the suckling period imposed by maternal protein deficiency during lactation resulted in elevated inositol triphosphatase activity (units per gram of wet tissue) in the ileum and lower phytase activity in the duodenum and jejunum. Activities of inositol triphosphatase in the duodenum and jejunum and phytase in ileum were unaffected. Postweaning nutritional rehabilitation resulted in elevated specific activities of both enzymes in all segments; however, activities of whole segments were similar to the corresponding control values.

Three chemotherapy studies of tuberculous meningitis in children.

Chemotherapy studies were undertaken in 180 patients with tuberculous meningitis. They were treated for 12 months with 1 of 3 regimens: the first consisted of streptomycin, isoniazid and rifampicin daily for the first 2 months, followed by ethambutol plus isoniazid for 10 months; in the second, pyrazinamide was added for the first 2 months, and in the third, rifampicin was reduced to twice weekly in the first 2 months. Steroids were prescribed for all the patients in the initial weeks of treatment.

Effects of pre- and postweaning undernutrition on polyphosphoinositide pools in rat kidney.

The effects of undernutrition on polyphosphoinositide levels in rat kidneys removed and frozen immediately after animal death or 10 min later were determined. Weanling (21-day-old) rats of dams fed a 5 or 22% protein diet and litters fed either normal or protein-deficient diets for an additional six wk were used. Nutritional deprivation lowered phosphatidylinositol-4-phosphate (PtdIns4P) preferentially (35-40%) but preserved phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P2) at weaning.

Inositol phosphatase in developing rat duodenum, jejunum and ileum.

Inositol phosphatase and phytase activities in different segments of the rat small intestine were measured during postnatal development. In the duodenum and jejunum, inositol phosphatase activity (units/g tissue) was low during the suckling period and increased at weaning, reaching a peak of activity at 4 weeks of age. In the ileum, peak activity was observed during the suckling period with a sharp decline at weaning.

Studies on hydrogen bonds. Part V--Hydrogen bonding in energy minimization studies of peptides.

An energy term, representing the N-H...

Studies on inositolphosphatase in rat small intestine.

The possibility that inositolphosphatase differs from other intestinal phosphatases was tested by comparing several enzymatic characteristics of phosphatase activities of rat intestinal homogenate acting on various specific substrates. Optimum pH and temperature, Km, Vmax, heat stability, inhibition and metal ion requirement studies suggest that inositolphosphatase differs from phytase and p-nitrophenylphosphatase. Furthermore, we found that inositolphosphatase activity was about 2 times higher in duodenum and jejunum than ileum.

Effect of ethanol on rat brain polyphosphoinositides.

Female rats were allowed to consume ethanol during gestation and lactation, and brain polyphosphoinositides of the 21-day-old pups were quantified. Ethanol intake prevented the disappearance of the metabolically labile pools of phosphatidylinositol-4-phosphate and phosphatidylinositol-4,5-bis-phosphate, which are rapidly degraded in the control group. In contrast, preweaning undernutrition left the size of these pools virtually unchanged, indicating a differential effect of the two nutritional regimens.

Occurrence of a single helix of the collagen type in globular proteins.

The occurrence of an eight-residue long segment of polypeptide chain in collagen helical conformation has been detected in bacteriochlorophyll a-protein by the application of an algorithm for identifying secondary structures in globular proteins from their alpha-carbon positions. This segment spans residues 277 to 284 of the protein and is the longest known stretch of collagen helix to be observed in globular proteins.

Studies on polyphosphoinositides in developing rat brain.

Polyphosphoinositides in rat brain exist in two forms: the metabolically active form that is readily attacked by the polyphosphoinositide phosphohydrolases, and the inert form that is attacked by the enzymes at a slower rate. The two pools continue to increase even during the postweaning period, suggesting a role in glial as well as myelin development apart from their role in neurons.

Effects of preweaning undernutrition and continued postweaning protein deficiency or nutritional rehabilitation on polyphosphoinositides in rat brain.

Metabolically inert polyphosphoinositides seem to play an important role in the structural development of neurons, glia, and myelin. The metabolically active pool of PhIpp appears to be important for the functional development of glia and myelin during the postweaning period, whereas PhIp seems to be more important for the functional development of neurons during the preweaning period. Neonatal undernutrition reduces the concentrations of structural polyphosphoinositides and metabolic PhIp while metabolic PhIpp remains unaltered.

Lipid composition of gray and white matter in developing rat brain.

The lipid composition of gray and white matter was studied in the developing rat brain. For this purpose, gray and white matter were separated from the brains of rats from different age groups and were used for the estimation of moisture and lipids. The moisture content of both gray and white matter decreased with age, but the decrease was more significant in the latter.

Effect of thiamine deficiency and undernutrition on the lipid composition of rat spinal cord at 21 days of age.

Maternal thiamine deficiency and undernutrition are found to cause significant deficits in body and spinal cord weights of the offspring at 21 days of age. The concentration of different lipids is found to be decreased significantly in both experimental groups as compared to normal controls. However, these deficits do not seem to differ between the undernourished and the thiamine-deficient groups.

Effects of nutritional rehabilitation on the content and lipid composition of brain gray and white matter of neonatally undernourished rats.

Neonatal undernutrition affects the content and lipid concentrations of gray and white matter. Nutritional rehabilitation reverses the deficit observed in gray matter. In the case of white matter the lipid concentration but not the content comes back to normal.

Identification of secondary structures in globular proteins--a new algorithm.

A new algorithm has been developed for identifying helices, extended structures, and bends from the positions of the alpha-carbon atoms using the virtual bond approach. The parameters used are two virtual bond angles (delta 1 and delta 2), the virtual dihedral angle (theta), and the distance (D) between the terminal alpha-carbon atoms of the tripeptide. The criteria for classification have been worked out by model building as well as from proteins whose complete secondary structures are known.

Effects of maternal thiamine deficiency on the lipid composition of rat whole brain, gray matter and white matter.

Studies were made of the effects of maternal thiamine deficiency on rat whole brain, gray matter and white matter lipids. Mothers were fed a high protein diet (controls) or thiamine deficient high protein diet (thiamine deficient, TD) from 14th day of gestation through lactation. An additional group (pair fed control, PFC) was pair fed with the thiamine deficient group.