Martin B. Williamson

Ionography: Some aspects of ion migration on paper in an electric field

Abstract The relationships that exist between the mobility of amino acids migrating on paper under the influence of an electric field, and the pH of the solution, the ionic strength, the time and the voltage across the paper are presented. The rate of migration bears a linear relation to the potential gradient and to the time. The isoelectric points of histidine and glutamic acid have been determined to be 7.6 and 3.1, respectively.

Effect of Cystine and Methionine on Healing of Experimental Wounds.

Summary The effect of methionine and cystine on the healing index of standard experimental wounds in rats was determined. Since both amino acids have the same effect, per equivalent of sulfur, it is concluded that methionine is converted to cystine before being used in the healing process. When the utilization of methionine is blocked by ethionine, cystine is ineffective, indicating that some methionine, per se, is required for the healing of wounds. There appears to be a correlation between the healing index and the retention of amino acid sulfur in excess of that expected on the basis of nitrogen retention.

Relation of protein nutrition to the healing of experimental wounds.

Summary Wounded rats were kept on diets containing varying amounts of different proteins and “protein sulfur”. There appears to be no relation between the amount of protein nitrogen fed or retained by the rats and the rate of healing. However, the “protein sulfur” retention appears to be correlated with the rate of healing. It is suggested that the amount of retained sulfur in excess over that utilized for normal tissue protein synthesis is an important factor in determining the rate of healing of experimental wounds.

Metabolism of nucleic acids during regeneration of wound tissue. III. The rate of formation of DNA

Abstract The rate of formation of RNA in regenerating wound tissue of rats was studied by following the uptake of P32. Total cellular RNA was found to be formed most rapidly during the early stages of regeneration; the rate of formation decreased with time. The incorporation of P32 into the RNA of the microsomes followed a similar pattern. The RNA in the nuclei of the cells, however, appeared to be formed more rapidly as regeneration progressed. The incorporation of P32 into the microsomal RNA was so much greater than that in the nuclei that the pattern of formation of the latter was masked in the studies on the total cellular RNA. A scheme is suggested relating the rate of formation of the RNA from different parts of the cell to the synthesis of different types of protein.

A modified two-dimensional paper chromatographic system for the separation of DNP-amino acids

Abstract The two-dimensional separation of DNP-amino acids by solvent systems which appear to overcome most of the shortcomings of previously described solvent systems is described. The organic solvent consists of n -amyl alcohol saturated with 0.05 M phthalate buffer at pH 6.0; the aqueous solvent consists of 1.5 M sodium sulfate containing 0.05 M phthalate buffer (pH = 6.0).

Utilization of Sulfur Amino Acids During Healing of Experimental Wounds.

Summary Wounded rats, injected with L-methionine-S35, accumulate the radio-sulfur in the wound tissue, even when the S35 content of the other tissues is decreasing. The largest part of the S35 in the wound tissue appears as cystine-S35. The rate of deposition of cystine in the regenerating wound tissue is greater than that of methionine. The rate of healing (as measured by the healing index) is a function of the cystine content of the wound tissue.

The terminal free carboxyl groups of pepsin

Abstract The application of three methods to the determination of the terminal free carboxyl groups in pepsin has been described. It was determined that pepsin has two terminal free carboxyl groups, both of which are alanine.

Excretion of Sulfur During Healing of Experimental Wounds.

Summary The effect of wounding on metabolism of the sulfur amino acids was studied by following the excretion of sulfur in normal and wounded rats. After wounding, there is a relative retention of sulfur, even though a greater amount of nitrogen than normal is excreted. Studies with S35 labeled cystine and methionine indicated that the metabolism of these amino acids is greater in wounded than in normal animals.

Catalysis of formation of mixed disulfides between cystine and β-globulins by copper ions☆

Abstract The ability of glutamate to inhibit the reaction between cystine and proteins to form mixed disulfides appears to be due to the formation of a complex between the copper ions and the amino acid. The copper ion seems to be the only divalent ion which can accelerate the rate of formation of the mixed disulfide.

Incorporation of cystine into the proteins of regenerating wound tissue

Abstract A procedure to distinguish between cystine bound into protein by peptide bonds and that associated with the protein as prosthetic groups by disulfide bonds only has been devised. This distinction is achieved by reaction of the cysteine and cystine in the protein with sodium sulfite in alkaline medium and simultaneous separation of the resulting thiosulfate derivatives by dialysis. Of the total cystine in regenerating wound tissue proteins, 6.6% is bound by disulfide bonds only. This fraction of the half-cystine residues turns over very much more rapidly than do the cystine residues in the protein bound by peptide bonds. The formation and turnover of liver proteins, as indicated by cystine-S 35 incorporation, is much more rapid in wounded than in normal rats. Wounding also appears to have the effect of increasing the proportion of half-cystine residues linked to the liver proteins by disulfide bonds only.