Richard J. Block

Synthesis of sulfur amino acids from inorganic sulfate by ruminants.

Summary Radioactive sodium sulfate was fed to a cow, milk was collwted for several days, and the proteins were isolated. The proteins showed apprmeciable radioactivity. From the hydrolysate of the radioactive proteins cystine and methionine were separeated on chromatograms, and eluted. Both cystine and methionine contained radioactive sulfur in appreciable amounts.

Amino acids in posterior pituitary protein.

Abstract Posterior pituitary protein is composed of 16 amino acids. These have been determined after acid hydrolysis by means of paper chromatography. The results have been compared with those of du Vigneaud, Pierce, and Turner, who analyzed the oxytocic and vasopressor polypeptides of the posterior pituitary.

Carboxymethylcysteine Metabolism, its Implications on Therapy in Cystinuria and on the Methionine-Cysteine Relationship:

In continuation of our experiments on sulfur metabolism, the behavior of carboxy-methyl-S-cysteine 1 (I) was investigated. (We are indebted to Dr. L. Michaelis for suggesting this compound for study.) Carboxyl-methyl-S-cysteine, like methyl-S-cysteine 2 does not support the growth of rats on a sulfur deficient diet, indicating that (I) does not yield cysteine (IV) in the course of its metabolism. Three and six-tenths grams of (I) were administered to a normal human being, while 7.2 and 14.4 gm. respectively were given to 2 cystinurics. The substance was not toxic and yielded in the urine neither cystine nor -SH compounds. In the normal, the sulfur of (I) was only partially oxidized (40%), the larger portion (60%) being excreted as undetermined neutral S. Part of this neutral S was apparently a disulfide, since there appeared in the urine a strong cyanide-nitroprusside reaction, while the Sullivan test remained negative. The urine was discarded before the probable nature of this disulfide was realized. Following the ingestion of (I) by the cystinuric patients, about 15% of the extra sulfur excreted was inorganic sulfate and 85% undetermined neutral S. Cystine excretion remained practically unchanged as indicated by the Folin photometric method, 3 but when measured by the Sullivan and Lugg-Sullivan methods, it dropped from one gm. to 200 mg. per day. These various findings seemed to indicate that part of (I) was excreted presumably as the unchanged compound, that part of it was oxidized to yield inorganic sulfate, and that another portion was excreted as an intermediate which contained sulfur in the form of a disulfide linkage. As a result of previous experiments, 4 and from the chemical formula of (I), it was reasonable to assume that the excretion of a disulfide resulted from the oxidation of an -SH compound derived from carboxymethylcysteine.

A New Method for Separation of the Basic Amino Acids from Protein Hydrolysates.

Summary A method is described for the separation of ammonia, arginine, histidine, and lysine from the other constituents of protein hydrolysates, based on the use of synthetic ion exchange resins. The procedure is especially valuable for the preparation of concentrates of the basic amino acids.

A comparative study on two samples of neurokeratin

Abstract 1. 1. Samples of neurokeratin of human and porcine origin, prepared approximately 60 and 20 years ago, respectively, have been compared with respect to their amino acid pattern. These two preparations appear to have approximately the same general distribution of amino acids. 2. 2. Neurokeratin yields approximately 4.2 g. arginine, 2.9 g. histidine, 6.3 g. lysine, 7.2 g. tyrosine, 1.3 g. tryptophan, 13–15 g. phenylalanine, 4.3 g. cystine, 2 g. methionine, 3.3 g. serine, 9.2 g. threonine, 15 g. leucine, 11 g. isoleucine, 5.7 g. valine, 5.0 g. glycine, 9.1 g. alanine, 11.9 g. glutamic acid, 3.7 g. aspartic acid, and 3.4 g. proline/16.0 g. nitrogen in the original protein. Hydroxyproline was not found.

Quantitative Paper Chromatography A Simplified Procedure

Summary Two methods are described which permit the estimation of colored substances on one-dimensional and two-dimensional paper chromatograms with a minimum expenditure of time and material.

Studies on bovine whey proteins. III. The preparation of crystalline α-lactalbumin and β-lactoglobulin from ferrilactin

Abstract Crystalline α-lactalbumin and β-lactoglobulin were prepared via ferrilactin from pasteurized skimmed milk. The method is compared with more conventional procedures.

Studies on bovine whey proteins. II. Removal of iron from the ferric derivatives of the whey proteins

Abstract 1. 1. The removal of the iron from ferrilactin (ferric salt of the bovine whey proteins) has been accomplished by (a) reduction with SO2, (b) reduction with sodium dithionite (Na2S2O4), and (c) the exchange of Fe+++ with H+ by strong cation-exchange resins from an acid solution. 2. 2. A denatured mixture of whey proteins is formed on long contact with a saturated solution of sulfurous acid in the presence of iron salts which is not heat-coagulable at pH 6.7–7.0, and which, although readily digestible in vitro, is of poor biological value unless supplemented with methionine, tryptophan, and arginine. 3. 3. Two protein fractions arise from the dithionite treatment; one is polydisperse electrophoretically and is coagulable by heat. The other has the same ionic mobility at pH 8.6 as β-lactoglobulin and, like β-lactoglobulin, is coagulated by heat at pH 6.7–7.0. 4. 4. Removal of Fe from ferrilactin by ion exchange results in a protein preparation consisting of components having the same ionic mobilities as the principal whey proteins (α-lactalbumin, β-lactoglobulin).

Preparation and amino acid composition of salmin and clupein.

Summary A simplified procedure for the preparation of salmin and clupein is described. The amino acid content of clupein as well as salmin has been estimated.

Metabolism of d- and l-methionine.

Previous investigation of the physiological rôle of methionine in the animal organism led the writers to conclude that “methionine, like cystine, is capable of unmistakably stimulating growth in albino rats subsisting on a basal diet poor in cystine. 1 , 2 It was pointed out 2 that this observation immediately raised various questions relative to the intermediary metabolism of methionine. Referring to one of these problems, we stated: “It is obvious, of course, that, since the addition of methionine (dl) to the diet of animals subsisting on the regimen previously described leads to growth stimulation, the study of the physiological behavior of …. the separate optically active forms of methionine becomes important. ”These compounds have been investigated with the following results. Methionine was synthesized and resolved according to the methods of Windus and Marvel. 3 , 4 d-Methionine as well as the naturally occurring l-methionine stimulates growth in the rat ingesting our cystine-methionine deficient diet, (cf., the results of similar experiments on tryptophane and cystine. 5 , 6 , 7 , 8 The formyl derivatives of the 2 optical isomers of methionine also were tested. The administration of formyl l-methionine causes increments of body weight similar to those produced by both l- and d-methionine. On the other hand, formyl d-methionine apparently cannot be utilized by the animal organism for growth under the conditions of our experiments. Analogous observations have been made on the physiological availability of the acetyl derivatives of d- and l-tryptophane. 6