COMXUNICXTIONS TO THE EDITOR
4.744
Vol. 82
form equivalent experiments with chymotrypsin. The results of these experiments are shown in Table I . Xgain the sum of the oxidation constants
but the solutions were examined only by paper chromatography and ultraviolet spectral measurements; we repeated these experiment^,^^^ b u t were unable to obtain the chromanol. Other reaction TABLEI conditions successfully converted hexahydrocoRATECOXSTANTS FOR PHOTOOSIDATIUX OF C H V M O T R V P ~ Ienzyme N Q4 to 7,8-dimethoxy-2,5-dimethyl-2-(4',8',Property assayed k (inin.-') 12'-trimethyltridecy1)-6-chromano14; such condiErizi-rne activity" 0.6'7 tions with coenzyme Qlo apparently gave chroAccessible histidine .32 nianol formation with concurrent cyclizations of the -4ccessible methionine ..XI 10-unit isoprenoid side chain. The product4 lacked I iiaccessible I1 ist idirie ,022 detectable unsaturated isoprenoid units by n.m.r. I iiaccessiblc met l i iunirie . 037 data. Others5 attempting to prepare ubichroTyrosine , 01 nianol reported materials with unexpected properTryptophan . 013 ties, possibly due to side chain cyclization. Xss;t~-crl b!. rate hydrolysis of acetyltyrosine etliyl -1 solution of coenzyme Qlo hydroquinone in ester. acetic acid containing potassium bisulfate was for the accessible histidine and accessible methioniiie rei'luxetl one hour and then concentrated. X soluis approximately equal to the observed rate con- tion of the residue in Skellysolve B was waterstarit of ().(;; iiiiri:-l for loss of enzyme activity. washed and chromatographed on Florisil. FracThese data therefore provide presumptive evi- tions eluted with ether-isooctane yielded the dence for amlogous involvement of both the histi- chromanol I1 which could also be purified by distildine and methionine in these two enzymes and lation in vucuo. The 60 megacycle n.m.r. spectrum hence support the hypothesis3 that the bond chang- of the oily product in carbon tetrachloride is the ing or "catalytic" amino acids may be similar in most critical criterion of its identity; tau (7)4.84 (-OH); 4.96 (HC=); 6.12 and 6.25 (CHaO-); enzymes of widely diverse specificity. 7.98 (CH3C= ring); The inference that the thioether group of a 7.50 triplet (-CHsC=); niethioriyl residue is involved in enzyme catalysis S.02 (=C(CH2)nC=); 8.40 (CHsC=); 8.73 (CHSis of particular interest since this group has nu C-0). This spectrum excluded a coumaran nucleus.6 Ultraviolet spectrum : Xmax 292 mp, significant acidic or basic properties in aqueous FI'. = 3s; infrared spectrum, band a t 2.85 solutions, but i t is a powerful neighboring group as d l p (-OH), no band for C=O in the 6 1.1 region and indicated by the reactivity of mustard g a s 5 a band a t 9 p . ( 5 ) Ct J . Hine, "Physical Organic Chemistry," hIcCraw-Hill Bouk -1nnZ. Calcd. for C5gH9?04:C, Sl.S9; H , 10.72. Co., X c w \-or!:, pi. U.,19.56. R R O O S H A V E S S A T I O S A L 1,ABOKATURY IY. J . K A Y ,J R . Found: C, S2.11; H, 10.50. CPTOS,SEW YORK 14. G . L A T H A X , J R . The Qli, hydroquinone (I) and the chronianol THEROCKEFELLER INSTITUTE $1. XATSOLLIS I I are not clearly distinguishable by ultraviolet SEK YORKCITY21, S. Y. L).E. K C S H L A N D , J R . maxima alone in mixtures, and by infrared data, RECEIVED J U L Y S, 1960 but are differentiated by RI and n.m.r. compari
