Dec. 20, 1957
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himbone (VI). l 1 The correlation of yohimbinetype alkaloids with D / E trans fusion with those of D,/E cis juncture thus is accomplished. The above data illustrate unambiguously for the first time that the only center of asymmetry common to all yohimbine-type alkaloids is C-15.12*13 (11) T h e Schmidt reaction of tetrahydroserpentic acid and tetrahydroalstonic acid does not lead t o ketones directly, b u t instead produces stable isocyanates. These results and further d a t a will be discussed a t a later time. (12) This fact was pointed o u t by A. K. Bose, B. G. Chatterjee and R . S. Iyer [ I n d . J. Pharm., 18, 185 (1956))in connection with their discussion of t h e absolute configuration of yohimbine alkaloids, based on molecular rotation difference data. (13) T h e authors are most grateful t o Drs. Huebner, Lucas, MacPhillamy and Schlittier for a generous supply of t h e compounds needed for this study and t o t h e Institute of Atomic Research, Ames, Iowa, for t h e use of a Baird infrared spectrophotometer.
DEPARTMENT OF CHEMISTRY ERNESTWENKERT IOWA STATE COLLEGE ERNEST W. ROBB AMES,I o m ~ X. V. BRINGI RECEIVEDNOVEMBER 6, 1957 OBSERVATIONS OB NEW PHENOMENA I N T H E FLUORESCENCE SPECTRUM OF A DIPHOSPHOPYRIDINE NUCLEOTIDE-LINKED DEHYDROGENASE
350
400
450
500
550
600
WAVE LENGTH, m p ,
Fig. 1.
shown to be competitive with respect to pyruvate and non-competitive with respect to DPNH, it is Boyer and Theorelll have reported that the wave inferred that this spectral change results from the length of the maximum intensity of the fluorescence formation of an LDH-DPNH-oxamate complex. spectrum of reduced diphosphopyridine nucleotide The concentration of oxamate required to reduce (DPNH) shifts from 450 mp to about 415 mp when the intensity of the LDH-DPNH fluorescent specD P N H combines with liver alcohol dehydrogenase. trum to half its initial value is approximately the Inspection of the figure presented by these authors value of K I when oxamate is used as an inhibitor indicates that the intensity of fluorescence of the for the LDH-catalyzed reaction between D P N H M. alcohol dehydrogenase-DPNH complex is approxi- and pyruvate, ;.e., approximately The curve labelled DPKH-LDH-lactate was obmately 1.8 times that of D P N H alone. We have made similar measurements with crys- tained when Na-L-lactate, a t a final concentration M , was added to LDH and DPNH talline heart muscle lactic dehydrogenase using the of 4.3 X Aminco-Bowman recording spectrophotofluorime- present in the concentrations used for the other terS2 The fluorescent spectra shown in Fig. 1 were curves. The wave length of maximum emission is measured in 0.05 M phosphate buffer, p H 6.88, a t shifted to 420 m p . The high concentration of lacroom temperature using an activating wave length tate required to produce this effect, which preof 340 mp. The curve labelled L D H was obtained sumably arises from an LDH-DPNH-lactate comM lactic dehydrogenase. The plex, is consistent with the observation that lacwith 8.4 X molecular weight of the enzyme was taken as tate has essentially no effect as an inhibitor of the 135,000.3 The curve for D P N H was recorded a t a LDH-catalyzed reaction between D P N H and pyruD P N H concentration of 2.5 X M . When Sate. The addition of oxamate to a concentration M results in the curve labelled DPNHD P N H and LDH were each present a t the concen- of 2 X tration used for the measurement of their separate LDH-LACTATE-OXAMATE. Results previously published from this Laboraspectra, the curve DPNH-LDH was obtained. The wave length of maximum fluorescent emission tory5v6indicate that a ternary LDH-DPNH-pyoccurs a t 430 mp as compared to 455 mp for ruvate complex is the reactive intermediate in the DPNH. Preliminary experiments indicate that reaction catalyzed by LDH. Kinetic results also the maximum shift in fluorescence occurs when the indicate that oxamate acts as an inhibitor by formratio of D P N H concentration to LDH concentra- ing an unreactive LDH-DPNH-oxamate complex. Since the addition of diphosphopyridine nucleotide tion is approximately four. (DPN), which does not itself fluoresce, t o LDH The addition of pyruvate to the DPNH-LDH system to a final concentration of 1.2 X M causes no change in the fluorescent spectrum of results in a rapid change to the spectrum of LDH LDH, the present results suggest that in the LDHalone. Surprisingly, the addition of oxamate to DPNH-oxamate complex the bonding electrons of the same concentration results in a similar change. D P N H are constrained in a configuration resemSince oxamate has been shown to be a powerful in- bling the aromatic ring of DPN. Moreover, since hibitor for the enzymatic reaction4 and has been no net reaction occurs, i t is possible that the LDHDPNH-oxamate complex is an abortive complex (1) P. D. Boyer and H . Theorell, Acta Chcm. Scond., 10, 447 (1956). similar in structure to the activated complex ( 2 ) R . L . Bowman, P. A. Caulfield and S. Udenfriend, Science, 122, formed between LDH, D P N H and pyruvate. 32 (1955). ( 5 ) M. T. Hakala, A. J. Glaid and G n'. Schwert, J B i d C b t , ~ . , (3) J. B. Keilands, J . Biol. Chem., 208. 225 (1954).
Sir;
(4) M. T. Hakala, A . J. Glaid a n d G. W. Schwert, F e d e m l i o n Proc.,
12, 213 (1953).
221. 191 (19561. , . (6) Y . Takenaka and G . XI', Schwert, ibid.,2 2 3 , 157 (195G)
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VOl. 79
This work was supported by research grants RG2941 and RG-4758 (S2) from the National Institutes of Health, Public Health Service.
is blocked by a preliminary incubation with ribonuclease to demonstrate that added MVALD is converted to MVA. The data of Table I show that DEPARTMENT O F BIOCHEMISTRY ALFRED D. WINER when a liver homogenate is preincubated for 30 DUKEUNIVERSITY SCHOOL WILLIAMB. KOVOA minutes with ribonuclease the counts found in the OF MEDICINE GEORGE \v. SCHWERT non-saponifiable fraction (NSF) or cholesterol DURHAM, NORTHCAROLINA (CHL) from 2-C14--MVAare markedly reduced and RECEIVED OCTOBER 14, 1957 the added MVA can be largely accounted for as such by microbiological assay of the digest. Similarly, with MVALD a sizable fraction of the highly MEVALDIC ACID I N THE BIOSYNTHESIS reactive and relatively unstable compound (dehyOF MEVALONIC ACID drates and decarboxylates to 3-methylcrotonaldeSir : hyde) is found in ANA. No microbiological acMevaldic acid (MVALD, 3-hydroxy-3-methyl- tivity is found when liver is preincubated with riboglutaraldehydic acid), a compound differing from nuclease without subsequent addition of ,MVA or mevalonic acid (MVA, 3,5-dihydroxy-3-methyl- MVALD or when ribonuclease is not used to block pentanoic acid) by an aldehyde rather than a pri- AIVA utilization. mary alcohol group a t position 5, has been suggested The accumulation of hiVA from NVALD in as an intermediate in “isoprenoid” synthesis. The this blocked system affords evidence that MVA is compound has now been synthesized by Shunk, EL derivable biologically from MVALD. Taken in al.,l who also showed that MVALD has essentially conjunction with the results of Amdur, et the no microbiological activity in the Lactobacillus acid- data strongly suggest that MVALD is a precursor ophilus 4963 assay for MVA2 but may be presumed rather than a product of MVIZ. TABLE I SUMMARY OF INCUBATIOS EXPERIMESTS WITH MEVALDIC , k I D (MVALD) AND MEVALONIC ACID (MVX) Each experimental flask contained 1 mg. ATP, 1 mg. DPN, 5 ml. rat liver homogenate (supernatant layers after centrifuging at 200 X g for 3 min.), and 5 mg. crystalline ribonuclease (Rlu’Ase) where indicated. T h e flasks were initially aerated with a stream of oxygen, stoppered and incubated with agitation (50 oscillations per min.) at 37” for 30 min. 0.5 mg. 2-Clt-MVA (calculated as the DL-dibenzylethylenediammonium salt, 14,000 c.p.m.) or 1.0 mg. MVALD (calculated as the DL-dibenzylethylenediammonium salt of the 5-dimethylacetal) prepared for use as described by Shunk, et al.,’ added where indicated followed by additional flushings with oxygen. Incubation continued for a total of 4.5 hours. Counts in the non-saponifiable fraction (NSF) were obtained on the petroleum ether extracts prior to preparation of the digitonides. Additional procedures employed including the preparation and counting of the cholesterol digitonides (CHL) as well a? the microbiological determination of MVA have been described in detail.6 Each experiment involves a different prep2 ration of liver homogenate. \ T e n
Activity of fraction, c p.m./mg.
I Y r3P
Expt. no.
Compd. added
Without RNAse
1
MVX MVXLD MVA MVALD MVA ;\-one
395
2
3
With RNAse
Without RNAse
33
1272
...
...
259
23
1158
...
...
309
135
...
...
...
to be a n intermediate in “isoprenoid” biosynthesis since the counts found in cholesterol are significantly reduced by the presence of MVALD when 2-CL4-MVAis incubated in the rat liver systema that synthesizes cholesterol. On the other hand, Amdur, et al.,4 found that 2-C14-5-di-T-MVAis incorporated into squalene by a particle-free system of yeast with no change in the T:CI4 ratio. If MVALD were an intermediate between MVA and squalene a decrease in the T: C1*ratio should have been encountered. We have employed a technique6 whereby the utilization of MVA by the rat liver enzyme systems
CHL
With RNAse
MVA found, mg. Without With RNAse RPiAse
64
10s
. . ’is0
...
0 0 0 0
51
0
...
0
0 ti4 0 29
0 51 0 30 0 50 0
Acknowledgments.-Supported by research grants from the National Science Foundation and the National Institutes of Health. We are indebted to Dr. Karl Folkers, Merck Sharp and Dohme Laboratories, Rahway, New Jersey, for the mevaldic acid (3-hydroxy-3-methyl-5,5-dimethoxypentanoic acid N,N l-dibenzylethylenediammonium salt) and to Drs. Charles S. Miller and James 11 Sprague, hierck, Sharp and Dohme Lltboratories, West Point, Pennsylvania, for the 2-C14-nievalonic acid (3,5-dihydroxy-3-methylpentanoic acid N,N’dibenzylethylenediammonium salt). GRADUATE SCHOOL OF XUTRITION CORNELL UNIVERSITY ITHACA,NEW YORK
LEMUELD. WRIGIIT MONIQUE CLCLAND BIRENDRA S. DUTTA
(1) C. H. Shunk, B. 0. Linn, J. W.Huff, J. L. Gilfillan, H . R. Skeggs JANE S. NORTON and K. Folkers, THISJ O U R N A L , 79, 3294 (1957). (2) H. R. Skeggs, L. D. Wright, E. L. Cresson, G. D. E. MacRae. RECEIVED OCTOBER 18, 1657 C. H. Hoffman, D. E. Wolf and K. Folkers, J . B a c l r t i o l . , 73, 519 (1956). ( 5 ) L. D. Wright, 3f. Cleland and B. Sanz-Perez, material being (3) P. A. Tavormina, M. H . Gibhs and J. W. Huff, THIS JOURNAL, prepared for publication. 78, 4498 (1956). (6) L. D. Wright and M. Cleland, Proc. S O L .E x p l l . B i d ’Wed., 96, (4) B. H . Amdur, H. Rilling and K . Bloch, ibid., 79, 2616 (1957). 219 11957).
