in this research, the microstructural of low molecular weight 1,2-polybutadiene (1,2-pbd) was conducted by 1h and 13c nuclear magnetic resonance spectroscopy (nmr) to determine the isomeric contents of 1,4-cis, 1,4-trans and 1,2-vinyl in 1,2-pbd polymer structures. number average molecular weight for low molecular weight 1,2-pbd was measured by nmr techniques and the results were compared with ...

Cobalamin-dependent methionine synthase (MetH) is a modular protein that catalyzes the transfer of a methyl group from methyltetrahydrofolate to homocysteine to produce methionine and tetrahydrofolate. The cobalamin cofactor, which serves as both acceptor and donor of the methyl group, is oxidized once every approximately 2,000 catalytic cycles and must be reactivated by the uptake of an electr...

Previous investigations have shown that the incorporation in vitro of formate, formaldehyde, or the beta carbon of serine into thymine compounds of normal lymphatic tissues and tumors is greatly increased when deoxycytidine, deoxyuridine, or cytidine are added to the incubation medium (1, 2). The present study demonstrates that in the above tissues (a) methyl cytosine deoxyribonucleoside is not...

The active site of nitrogenase, the M-cluster, is a metal-sulfur cluster containing a carbide at its core. Using radiolabeling experiments, we show that this carbide originates from the methyl group of S-adenosylmethionine (SAM) and that it is inserted into the M-cluster by the assembly protein NifB. Our SAM cleavage and deuterium substitution analyses suggest a similarity between the mechanism...

The methyl group of nicotine has been shown to participate in transmethylation reactions involving methionine (3) and choline (8). De novo synthesis of radioactive nicotine from nornicotine, methioninemethyl-C14 and ATP was demonstrated recently in leaves of Nicotiana alata (9). In the present study the rate of metabolism of the methyl group of nicotinemethyl-C14 ancl the rate of transmethylati...

The title compound, C(6)H(13)O(3)PSe, was obtained in the reaction of 5,5-dimethyl-2-oxo-2-seleno-1,3,2-dioxaphospho-r-inane potassium salt with methyl iodide. The seleno-methyl group is in the axial position in relation to the six-membered dioxaphospho-rinane ring.

Protein arginine methyltransferases (PRMTs) catalyze the transfer of methyl groups from S-adenosylmethionine (SAM) to the guanidinium group of arginine residues in a number of important cell signaling proteins. PRMT1 is the founding member of this family, and its activity appears to be dysregulated in heart disease and cancer. To begin to characterize the catalytic mechanism of this isozyme, we...

S-Adenosyl-L-methionine (SAM) dependent methyltransferases (MTases) play crucial roles in many biological processes. The MTase of the dengue virus is of particular interest for the development of antiviral drugs against flaviviruses. It catalyzes two distinct methylation reactions at the N7 and the 2'O position of the viral RNA cap structure. Based on density functional theory (DFT) electronic ...

Methanol dimer (CD3OH)2 ion–molecule reaction is initialized by VUV ~vacuum ultraviolet! laser photoionization. The proton and deuteron transfers are the dominant reactions. The relative probabilities of deuteron transfer from the methyl group and proton from the hydroxyl group were measured as a function of VUV photon energy between 10.91 to 10.49 eV. According to those results, the probabilit...