48 14
COhI>ICiXIC.'.TIONS TO
THE
EDITOR
Yol. 70
low 1 M the value of Ks' begins to increase, slowly and then rapidly, and as the system approaches zero ionic strength the value of Ks' teiids to become very large. While the value of k3' generally de(10) Fellow of the Kettering Foundation, D a y t o n , Ohio creases with decreasing concentration of sodium BIopavsIcs RESEARCH LABORATORY or chloride, a t concentrations below 1 dl the value of THE DEPARTMEST OF MEDICINE HARVARD MEDICAL SCHOOL AND ~ I A R VMI A XR G O S H E S k3' ~ ~ decreases more rapidly than at concentrations BERTL. YALLEE above 1 dl and as the system approaches zero ionic IIOSPITAL PETERBEST BRIGHAM BOSTON15, MASSACHUSETTS strength the value of kQ appears to beconie very RECEIVED Aucvsi 1, 1937 small. -Although it is not possible to conduct an experiment in a system of zero ionic strength, it may be inferred from Fig. 1 that in such a system T H E EFFECT O F SODIUM CHLORIDE ON T H E the value of Ks may approach infinity and the value d@ha-CHYMOTRYPSIN CATALYZED HYDROLYSIS of k3 mav approach zero with the result that no rcO F METHYL HIPPURATE action may be observed. The implied inertness Sir: of a-chymotrypsin in reaction systems containing The development of the pH-Stat'~*has madeit possible to observe certain enzyme-catalyzed reactions no added sodium chloride may be a property of the in the absence of conventional buffers and to protein molecule per se, or may be due to a transthereby determine the effect of added salts upon formation of the active enzyme to species that are the rates of such reactions at a constant pH and at incapable of combining with the specific substrate. relatively low ionic strengths. I n the course of I n either case, the addition of sodium chloride leads such studies, i t has been observed that the initial to the formation of a more active enzyme. Results similar to but not identical with those rates of the a-chymotrypsin catalyzed hydrolysis summarized in Fig. 1 have been obtained with of methyl hippurate in aqueous solutions a t 25.0' and p H 7.90 0.01 and a t various initial specific methyl hippurate and other salts, e.g., lithium substrate concentrations are markedly dependent chloride, potassium chloride, sodium bromide and upon the presence of added sodium chloride. The magnesium chloride, and. with sodium chloride and nature of this dependency is most readily illus- another ester type of specific substrate, i.e., acetyltrated by a consideration of the separate depend- L-valine methyl ester. Therefore, it should be encies of the constants Ks' and k3' for the above realized that the case involving a-chymotrypsin, reaction system upon the concentration of added methyl hippurate and sodium chloride is not unique sodium chloride. It will be seen from Fig. 1 that but is representative of the general behavior of n number of similar systems. This work was supported by the National Institutes of Health and the Howard Hughes Medical Institute.
*
CONTRIBnTIOs S O . 2227 FROM TRE GATES ASD CRELLIN LABORATORIES OF CHEMISTRY CALIFORNIA ISSTITVTEOF TEcnsoLor:Y R. BRCCEMARTIN P A S A D E S A , CAI.IFORS;IA CARL S I E h l A S N J U L Y 18, 19.57 RECEIVED
T H E CONVERSION OF RUSCOGENIN TO 1$-HY DROXYPROGESTERONE
II
-
;ip
K; 6.0
A
Sir: 4.0 k;
- 3.0
4.0
1.0
2.0
MNoCI. Fig. 1.-Dependence of K's and k'3 upon concentration of sodium chloride; K's in units of M , k'3 in units of 10-3 .V/min./mg. protein-nitrogen per ml.
at concentrations of sodium chloride greater than 1 M the value of Ks' is essentially constant but as the concentration of sodium chloride is decreased be(1) C . F. Jacobsen and L. Leonis, C c i n p l . y e l i d . l ~ a vl n h . C n r l s h r v p , Sr.r. Ciiim., 27, 333 (1951). ( 2 ) J. B. Sielands a n d h I D . Cnnnrjn, A i i o l . C h c n . , 27, ?!I (1\l35).
The isolation oi ruscogcniii,: a steroiclal sa1)oh.enin from Rlr.jcli.7 nclrleufus L., :uid the recognition th:it this substmcc 1)ossesse.j the structure CJI' diosgenin with an atltlitional hytlrosyl group.' furnislied ail interesting poteiitial starting iiintcrinl ior novel compounds related to physicdogically active substances. lye wish to report here the synthesis of 1~-li~-clroxyprogesterone. \ \ M e it was believed at first t h t ruscogenin has its second hydroxyl group a t C-l!),? the n . d i oi Burn, Ellis mid Petrov,2as well :IS suhcequtii~work by Lapin.: indicates the hydroxyl to be a t C-1. 111 agrcenient with these authors, we bclieve the latter to be the case and wish to oficr xlclitional cvidtncc. -\uthentic (.'5Dj5 ruscogcnin tliacetate, 1) C 3trluii. H I . I ~ ! I I ,I' 1:lc,y -,nd !, i >; : " . c h i w n i . ! ,39,:101 [lG-,:i, :.nd referc!icc71i.te.! L ! C . S i n c i i :t:tx! H T.t::in, L! 5 , . , I 1 8 I,,.:, (4) I1 1.. L a p i n , Ccni:/ ,',',!!., 244, 30,:; . I G - T , '5' I t 1 3 pr,sst')lc 1 , i..!nte n o t only t h e ?5,D i
