The interaction of bleomycin A2 with DNA has been examined by fluorescence spectroscopy and proton magnetic resonance techniques. Fluorescence bands observed at 353 and 405 nm in the spectrum of bleomycin were assigned to the bithiazole and 4-aminopyrimidine rings, respectively. Quenching of bithiazole fluorescence by DNA was used to determine apparent equilibrium constants for the complex which, in 2.5 mM tris(hydroxymethyl)aminomethane buffer, pH 8.4, are 1.2 X 10(5) M-1 for bleomycin and 1.4 X 10(5) M-1 for tripeptide S, a partial acid hydrolysis product of the antibiotic. Uner these conditions, one molecule of bleomycin binds for every five to six base pairs in DNA. In the proton magnetic resonance spectrum of bleomycin, resonances emanating from the bithiazole rings and dimethylsulfonium groups are preferentially broadened and reduced in intensity in the presence of DNA, suggesting that these moieties bind most tightly to the polymer.

High-performance liquid chromatography/mass spectrometry (HPLC/MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used to characterize the procyanidin composition of the grape seed extract. The detection of the oligomers composed of (+)-catechin, (-)-epicatechin, and their galloylated derivatives in the grape seeds is demonstrated. With MALDI-TOF MS, oligomers up to nonamers were observed. The potential of the MALDI-TOF MS technique as a quantification tool is also discussed. The information presented in this study could lead to the determination of procyanidin content and their molecular weight distribution in grape seeds.

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the volatile trimethyl borate by codistillation with methanol, and the residue was heated 2 h at 85 "C, in vacuo to completely convert the aldonic acids into aldonolactones. Lower temperatures and/or shorter time periods resulted in partial conversion and the isolation of some free aldonic acids. Complete conversion is necessary because aldonic acids will not form N-propylaldonamide when treated with l-propylamine. Even though the amine is very basic, it did not cause epimerization under the conditions studied. Acetylation with pyridine and acetic anhydride requires 1 h and is quantitative. Dehydration reactions occur with the lactone (16) but not with the amide.Essentially the original aldoses have been converted into alditol acetates, and the original aldonic acids and aldonolactones have been converted into corresponding N-propylaldonamides. Calibration curves constructed by plotting detector response vs. milligrams of sample (1.2-6.7 mg) have a correlation coefficient greater than 0.995. A wider range of sample sizes can be accommodated by suitable concentration or dilution of the injected sample.There are a number of advantages to the new procedure. The method is able to handle complex mixtures of aldonic acids and aldoses. Alduronic acids can be determined by suitable modifications. Because the carboxyl group is kept, the stereochemical configuration of the sugar is maintained, unlike the differential method (2) wherein the lactone is reduced to the alditol. The new method adds a degree of versatility not found in most methods. The N-propyl group can be substituted easily by an N-butyl, N-amyl, or even an N-hexyl by replacing 1-propylamine by some other amine. The lactone will react under basically the same conditions to give a homologous derivative. The advantages are readily apparent in that the larger the N-alkyl group, the greater the elution time relative to the alditols or other possible compo-nents, e.g., phenyl P-D-ghcopyranoside. In fact, N-propylxylonamide coelutes with phenyl 0-D-glucopyranosides; by changing to N-amylamine, one is able to separate them into two peaks while maintaining the resolution seen in Figure 2. (5) Dmitriev, B. A.; Backinowsky, L. V.; Chizhov, 0. S.; Zoiotarev, 8. M.; Kochetkov, N. K. Analysis of a complex mlxture Involves a gas chromatographlc separation followed by a mass spectral search for Identification of each component. Thls Is an extremely tedlous andtime-consumlng process for fragrances and flavors whlch sometimes contaln hundreds of components. Thls presentatlon describes a computer pattern recognttlon method for the rapid ldentlficatlon of components in a complex mixture, the comparlson between the complete GC profiles of different samples, and the recognltlon of a group of compounds as a single entity. The central part of thls method is a comparlson algorlthm which compares the components In two mixtures uslng the K nearest neighbor classification rule. I t is Illustrated by comparing essential oils of dlfferent sources and by detectlng essentlal 011s In perfum...

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Nmr spin-lattice relaxation times Ti of F3CCOOH proton and the side-chain phenyl protons of poly(7-benzyl L-glutamate) ((BzlGlu)") were measured in (BzlGlu)"-F3CCOOH-CDCl3. T\ was affected by the solvent-induced helix-coil transition. F3CCOOH proton T, behavior was interpreted by a two-site model, i.e., F3CCOOH molecules bind to the (BzlGlu)" or are free in solution. The Ti values for the phenyl ring terminating the (BzlGlu)" side-chain increase before the onset of the helix-coil transition. This increase in side-chain mobility is discussed in terms of the effects of polydispersity and the concept of a side-chain secondary structure.