Fast Proton Exchange in Histidine: Measurement of Rate Constants through Indirect Detection by NMR Spectroscopy

Owing to its imidazole side chain, histidine participates in various processes such as enzyme catalysis, pH regulation, metal binding, and phosphorylation. The determination of exchange rates of labile protons for such a system is important for understanding its functions. However, these rates are too fast to be measured directly in an aqueous solution by using NMR spectroscopy. We have obtained the exchange rates of the NH₃⁺ amino protons and the labile NH^ε2 and NH^δ1 protons of the imidazole ring by indirect detection through nitrogen‐15 as a function of temperature (272 K<T<293 K) and pH (1.3<pH<4.9) of uniformly nitrogen‐15‐ and carbon‐13‐labeled L ‐histidine ? HCl ? H₂O. Exchange rates up to 8.5×10⁴ s^?1 could be determined (i.e., lifetimes as short as 12 μs). The three chemical shifts δ_Hi of the invisible exchanging protons H_i and the three one‐bond scalar coupling constants ¹J(N,H_i) could also be determined accurately.     

Biotechnological Innovations from Ocean: Transpiring Role of Marine Drugs in Management of Chronic Disorders

Marine drugs are abundant in number, comprise of a diverse range of structures with corresponding mechanisms of action, and hold promise for the discovery of new and better treatment approaches for the management of several chronic diseases. There are huge reserves of natural marine biological compounds, as 70 percent of the Earth is covered with oceans, indicating a diversity of chemical entities on the planet. The marine ecosystems are a rich source of bioactive products and have been explored for lead drug molecules that have proven to be novel therapeutic targets. Over the last 70 years, many structurally diverse drug products and their secondary metabolites have been isolated from marine sources. The drugs obtained from marine sources have displayed an exceptional potential in the management of a wide array of diseases, ranging from acute to chronic conditions. A beneficial role of marine drugs in human health has been recently proposed. The current review highlights various marine drugs and their compounds and role in the management of chronic diseases such as cancer, diabetes, neurodegenerative diseases, and cardiovascular disorders, which has led to the development of new drug treatment approaches.     

Synthesis of 2-deamino- and 2-deamino-2-nitroactinomycin D

A single step synthesis of 2-deaminoactinomycin D ( 3a ) and 2-deamino-2-nitroactinomycin D ( 2a ) arising from actinomycin D ( 1a, AMD ) is reported. Structural confirmation was made by nmr, ir and chemical conversion to known materials.     

Corrections to νe−νμ universality in neutral current interactions

We examine the effects of higher-order corrections on the universality between ν_μ and ν_e in the Weinberg-Salam model. The leading correction to neutral current amplitudes is an apparent difference in the values of sin²θ as measured by ν_μ and ν_e beams. The difference is .     

Signatures of neutral heavy leptons in neutrino-induced dilepton events

The tentative indication in some experiments of μ^?e⁺ or π^?μ⁺ events with unusual characteristics revives the speculation that neutrino-induced dileptons may contain a weak signal of neutral heavy lepton (L⁰) production. We study the characteristics of dileptons expected from the production of an L⁰ through a current of the form $\text{L}{}^0\text{γ}{}_{\mathrm{\alpha }}\text{(1+γ}{}_5\text{)ν}{}_{\mathrm{\mu }}$. Both quasi-elastic and deep inelastic excitation are investigated and a comparison is made with dileptons of charm origin. As an illustration of a model with a ν_μ→L⁰ transition, we discuss the 2-2 version of the SU(2) × U(1) model and comment on the role of the Higgs particle in such transitions.     

Os(VIII)-catalysed oxidation of sulfides by sodium salt of N-chlorobenzenesulfonamide

Catalytic activity of Os(VIII) in the oxidation of some twenty organic sulfides with sodium salt of N-chlorobenzenesulfonamide (CAB) has been investigated in alkaline (pH8.7) t-butanol–water (1:1 v/v) medium. Significant retarding influence of [OH⁻] on the reactivity is exhibited. The catalysed reaction is strongly accelerated in the presence of Hg(II). Imperfections are observed in the linear Hammett relationship in the case of –NO₂ substituents.