Studies on the antigenic structure of Vibrio cholerae. 7. Two acid-soluble protein fractions
Linton, R.W.; Mitra, B.N.
Indian Journal of Medical Research 22(2): 295-308
ISSN/ISBN: 0019-5340 Accession: 025571424
Two acid-soluble protein substances, A and B, have been isolated from a group of vibrios in which the following strains were included: cholera vibrios, cholera-like vibrios, smooth, smooth-rough and rough vibrios. The proteins of these vibrios belonged about equally to Protein I and Protein II as defined in the authors' earlier work. "A" substance, which dissolves out of the vibrios at 50[degree] C. in alcohol made 0.025 N with HC1, has a specific rotation of about[long dash]12.0[degree] (in N/2 alkali after 2 hrs. at 37[degree]) and a N distribution which is characterized by the possession of about twice the amt. of amide N and half the amt. of humin N occurring in the whole protein. "A" occurs in both the pseudo- and euglobulin fractions of the protein, appears to increase when the whole protein is kept for 2 weeks in distilled water at 10[degree], and is destroyed when extraction is attempted in 0.125 N HC1. Its yield is usually about 1-2% of the dried weight of the vibrios, although the authors were unable to arrive at completely constant results in respect to the amt. extracted. "B" substance was obtained after the removal of A by boiling the vibrios for 15 min. in 75% alcohol, diluted with normal saline, and made 0.05 N with HC1. The material removed by this method has a rotatory power of about[long dash]46[degree] and a N distribution indistinguishable from that of the whole vibrio protein. B is found in both the globulin fractions and, like A substance, comes in larger amts. from the euglobulin. Its yield does not appear to be affected by high concns. of HC1, nor does it increase in vibrio protein kept in the refrigerator in distilled water. In general, B substance is about 6% of the dry weight of the protein, but as in A the % yields are not constant. Comparison of all the chemical findings indicates that the A substance is similar from whatever type of strain or protein it is extracted. B substance differs markedly from A, but again is the same irrespective of source. B is closely allied in composition to the residue protein which remains after the 2 acid-soluble fractions have been removed, and is also identical with the whole protein, in so far as chemical methods allow us to judge. None of the fractions is toxic when given intraperit. to guinea-pigs, nor do they give rise to skin reactions indicative of toxicity when administered sub-cut. to rabbits.