Joseph L. Rabinowitz

Peptide formation in the presence of linear or cyclic polyphosphates

SEVERAL authors have reported the condensation of amino-acids in aqueous solutions using various “prebiotic” condensing agents, such as cyanamide1–3, cyanoguanidine4 and dicyanamide5. The yields are generally very low (up to 1 or 2 per cent), or are only higher in a pH range which is not believed to be that of primitive oceans (neutral to slightly alkaline)6.

Phosphorylation by way of inorganic phosphate as a potential prebiotic process.

Conditions can be created in which inorganic phosphates act as phosphorylating agents. Such reactions may have occurred in prebiotic chemical processes.

Lipid composition and de novo lipid biosynthesis of human palmar fat in Dupuytren's disease

Seventy-two surgically obtained Dupuytrens disease palmar-fat (DDPF) specimens and 18 location-matched speciments from patients not suffering from this disease (controls) were studied for their total lipid composition and de novo lipogenic activity. Incubation of “DDPF” with 1-[14C]acetate in oxygen produced [14C]palmitate and [14C]stearate in approximately equal yields as those obtained from “controls”. No [14C]octanate was formed in any of the palmar-fat preparations. The lipids and fatty acid analysis revealed differences; (a) DDPF specimens were richer in free fatty acids, methyl esters of fatty acids and freecholesterol than specimens of controls (b) DDPF specimens contained less phospholipids. (c) DDPF specimens showed a significantly higher content of octanoate and other short-chain fatty acids than specimens of controls. The above findings are not incompatible with the results expected if some mild hypoxia occurred in DDPF; this has been suggested in the statistical correlations observed for this disease and alcoholism with liver involvement.

Studies of nucleotides of growth-plate cartilage: evidence linking changes in cellular metabolism with cartilage calcification

The objective of this study was to examine the nucleotides of chick growth-plate cartilage and to measure the concentration of adenine nucleotides in the pre-mineralizing and mineralizing zones. Nucleotides were isolated from the two regions using a rapid-freezing technique and the concentration of individual components was ascertained by HPLC. The actual values of ATP, ADP, and other nucleotides in cartilage was low. The lowest values were recorded in the mineralized zone. In this latter zone the energy charge ratio and the ATP/ADP ratio were depressed. This was probably due to 02-related inhibition of mitochondrial oxidative activity . Additionally, the percentage of octanoate, a short-chain fatty acid that accumulates when aerobic metabolism is disturbed, was found to have increased in the calcifying zone. These findings suggest that calcification of cartilage is associated with hypoxia-related modulation of chondrocyte metabolism.

Electric discharge reactions in mixtures of phosphine, methane, ammonia and water

THE reaction of phosphine with water at high temperatures and pressures yields mixtures of orthophosphoric and phosphorous acids in various proportions, depending on the conditions1. Phosphine reacts with unsaturated hydrocarbons2,3, and carbonyl compounds4 such as aldehydes and ketones, to give rise to organic phosphines which are products containing C—P bonds. The α-amino-alkylation of white phosphorus and diphosphines with an amine and a carbonyl compound in aqueous solutions has also been reported5.

Studies on a glucuronolactone decarboxylase

1. n1. A particle-free enzyme system of rat kidney has been prepared which is capable of decarboxylating GL and GLA. When fortified with UTP, TPP, DPN, ATP and Mg++ maximal effects are obtained. The reaction is aerobic. n n2. n2. The enzyme system yields approximately 12% of CO2 which is predominantly derived from carbon-6 of GL and GLA. Increased yields may be obtained by further addition of enzyme.

The biosynthesis of radioactive estradiol I. synthesis by surviving tissue slices and cell-free homogenates of dog ovary

1. n1. 2-14C-acetate is incorporated into estradiol, estrone and cholesterol by surviving tissue slices and homogenates of dog ovary. n n2. n2. Under comparable conditions more acetate was incorporated into estradiol than into estrone. n n3. n3. The activity of estradiol and estrone obtained from tissues of animals in proestrus was greater than that of animals in anestrus.

Deposition of C14-Labelled Cholesterol in the Atheromatous Aorta.

Summary The results suggest that circulating cholesterol exchanges with available cholesterol pools of intima of human aorta. This exchange is slow. Cholesterol in the atheromatous plaques appears to exchange or accept circulatory cholesterol with the greatest difficulty. The highest exchange or depositions were observed for area of the arch of human aorta; abdominal part of aorta showed a smaller exchange. The media showed about the same cholesterol rate of exchange through length of aorta. A disk technic suitable for various types of quantitative assays of intima, media, etc. of the aorta was described.

Carbon isotope effects in enzyme systems. I. Biochemical studies with urease.

Abstract It has been shown that the urea-urease system is capable of hydrolyzing urea-C12 more rapidly than urea-C14 regardless of the concentrations of the labeled material. The average maximum effect observed in different experiments was of the magnitude of 10 ± 2f% at 37 °C. Recovered urease under the experimental conditions described excludes the probability that urea, or a carbon fragment, was incorporated into the enzyme. A modified technique for the collection of barium carbonate specimens and measurement of radioactivity at infinite thickness is described.

The effect of L-triiodothyronine on the fatty acidcomposition of human adipose tissue

Biopsies of subcutaneous fat were analyzed for lipid composition before and after the administration of L-triiodothyronine in 6 obese patients. A slight decrease in total lipids occurred but there were insignificant changes in the fatty acid composition. The study demonstrates the striking constancy of the fatty acid composition of human adipose tissue and its resistance to change.