A chemical study of cystine from kidney stones. ∗

Abstract

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 [α_D ²⁰] = −242.6°. Neuberg and Mayer 2 report −224° for the optical rotation of “protein” cystine and −206° for “stone” cystine.