Walter F. Hoffman

Applicability of a Differential Analyzer to Determination of Protein Fractions by the Electrophoretic Technic

This laboratory has found it advantageous to use a differential analyzer in place of a planimeter in connection with determination of concentrations of plasma protein fractions from electrophoretic patterns. The differential analyzer is an analogue computer developed at the Massachusetts Institute of Technology under the direction of Dr. Vannevar Bush. One was recently acquired by Wayne University. Its use was made available to us and the work was carried out at Wayne University Computation Laboratory under the direction of Prof. Arvid W. Jacobson. Although the primary purpose of the analyzer is the solution of differential equations (1) the principles upon which it operates are quite simple. All quantities involved in the calculations are represented by the rotation of shafts. The fundamental unit is the integrator which is shown in Fig. 1. The disc A turns the wheel B by friction. Hence, a slight amount of rotation, δW of wheel B will be proportional to the product of the corresponding rotation, δY of disc A and the distance U of wheel B from the center of A; i.e., W = k·UΔV Thus, if u and v vary, the rotation of wheelnism of Fig. 1 is represented by the symbol marked integrator. The symbol marked input table is a function unit used to generate the function F(X) in the machine. A graph of this function is plotted on the table, and the machine moves the carriage, to which an index or bulls-eye is attached, horizontally across the input table, while the operator works the crank in such a way as to keep the bulls-eye on the curve. The speed of the horizontal motion of the bulls-eye can be varied by the operator, depending on the slope of the curve to be followed.

An immunological and chemical study of the alcohol-soluble proteins of cereals.

The prolamines, or alcohol-soluble proteins, are the characteristic proteins of cereal grains. These proteins were isolated from wheat, Triticum vulgare, durum, Triticum durum, emmer, Triticum dicoccum, spelt, Triticum spelta, einkorn, Triticum monococcum, rye, Secale cereale, oats, Avena sativa, barley, Hordeum vulgare, corn, Zea mays, kafir, Andropogon sorghum, teosinte, Euchlaena mexicana Schrad., and sorghum, Sorghum vulgare, and subjected to chemical and immunological study. The chemical study included the nitrogen distribution by the Van Slyke method, the free amino nitrogen, the free carboxyl groups, the true ammonia nitrogen, the cystine and tryptophane content, and the acid and alkali binding at various hydrogen ion concentrations and at different temperatures. This study showed certain similarities of chemical composition among the prolamines, as a class, as contrasted with the composition and behavior of such proteins as casein and fibrin. The chemical evidence suggested that the prolamines studied might be grouped into a “wheat group”, which would include the proteins isolated from the genus Triticum, and a “corn group” including those isolated from maize, teosinte, kafir, and sorghum. The genetic behavior of these groups has been extensively studied by plant blreeders, although relatively more work has been done upon the wheat group. Sakamura, 1 Kihara, 2 and Sax 3 have shown that T. monoccum is characterized by having 7 chromosomes, that T. dicoccum and T. durum have 14 chromosomes, and T. vulgare and T . spelta have 21 chromosomes.

A rapid method for the determination of the moisture content of expressed plant-tissue fluids

The moisture content of expressed plant saps can be measured by determining the refractive index of the sap using an Abbé refractometer provided with a special “sugar scale.” In a series of determinations we have found that more accurate results can be obtained by the refractometric method than can be obtained by drying weighed portions of the saps in a vacuum oven. The results are fully as accurate as are those obtained by drying in vacuo at room temperature over sulfuric acid. The great advantage of the method lies in the fact that only 2 or 3 drops of sap are necessary and that the entire time of measurement need not exceed two minutes. It appears probable that the method may be applied to other biological fluids. A more extended account of the method will appear in a botanical journal.

A chemical study of cystine from kidney stones.

In 1923, Dr. C. E. Tennant 1 reported a surgical case in which 15 stones having a total weight of 73 grams were removed from a kidney. He noted that these stones were composed chiefly of cystine, which, upon purification, crystallized in hexagonal plates. Inasmuch as this material offered an unusual opportunity of again investigating the old question—is stone cystine identical in chemical composition with protein cystine—we secured, through the kindness of Dr. Tennant, a number of the kidney stones, and have analyzed them and prepared certain organic derivatives of the “stone” cystine. Our data, in summary, are: 1. 5.20 grams of the cystine stones yielded 4.84 grams, or 93 per cent of pure cystine crystallizing in typical hexagonal plates. Qualitative tests on the filtrate from the cystine crystallization indicated that small amounts of calcium and phosphate were present. Neuberg and Mayer 2 state that “protein” cystine crystallizes in hexagonal plates but “stone” cystine crytallizes in needles. We have found “protein” cystine to crystallize in the typical hexagonal plates, whereas our “isomeric” 3 cystine, prepared from “protein” cystine by long boiling with 20 per cent HCl crytallizes in microscopic needles. We have found “protein” cystine to crystallize in the typical hexagonal plates, whereas our “isomeric” 3 cystine, prepared from “protein” cystine by long boiling with 20 per cent HCl crytallizes in microscopic needles. 2. The cystine crystals analyzed for 11.63 per cent nitrogen (theory 11.65 per cent) and 26.55 per cent sulfur (theory 26.67 per cent), and a 1 per cent solution in approximately 0.1 N HCl had a specific optical rotation of [αD 20] = −242.6°. Neuberg and Mayer 2 report −224° for the optical rotation of “protein” cystine and −206° for “stone” cystine.

Quantitative Estimation of Chlorides and Sulphates in Expressed Plant Tissue Fluids

Methods have been described for the rapid and accurate determinations of chlorine and sulphates in plant saps. These methods are essentially as described by Wetmore for chlorides in blood and by Benedict for sulphur in urine. The manipulations are simple, and neither elaborate apparatus nor exceptional skill is required.