2440-79-1Relevant articles and documents
Concentration- and Structure-Dependent Effects of Amides on Protease Activity in Organic Solvents
Yamamoto, Yasuhito,Kise, Hideo
, p. 1367 - 1370 (1994)
The catalytic activity of α-chymotrypsin (CT) in the transesterification of N-acetyl-L-tyrosine methyl ester to its ethyl ester in aqueous-organic media was markedly enhanced by replacing a part of water with foramide.The activity of CT was strongly dependent on the formamide/water ratio, and excess formamide retarded the activity.Addition of formamide to reaction mixtures at constant water contents exhibited similar activation-deactivation profiles for CT.A kinetic study revealed that the rate acceleration is due to an increase in kcat rather than a change in Km.At a given concentration of amides (0.5 M, M = mol dm-3), propionamide and DMF were much less effective than formamide for activation of CT.The results suggest that foramide interacts with CT in a different way from water.
Effects of metal salts on the structure and activity of α-chymotrypsin in ethanol/water
Sasaki, Toshiya,Kise, Hideo
, p. 1321 - 1325 (1999)
The catalytic activity and circular dichroic (CD) spectra of α- chymotrypsin (CT) were measured in ethanol/water (95/5, v/v) solution containing small amounts of metal salts. Although the catalytic activity of CT increased upon the addition of all the metal salts used, the magnitude of activity increase was different for different metal salts. Especially, calcium acetate accelerated the transesterification of amino acid up to 6 fold at 100 μM. The secondary and tertiary structures of CT were also changed by metal salts, as studied by CD measurements. The effects of metal salts on the stability of CT in ethanol/water were also studied, and it was found that the residual activity of CT after 7 days in ethanol/water in the presence of Ca(OCOCH3)2 was about 20% of the initial activity. The change in activity was closely correlated with the change in the mean residue ellipticity of CT at 208 or 230 nm.
Increase of catalytic activity of alpha-chymotrypsin by metal salts for transesterification of an amino acid ester in ethanol.
Sasaki,Kise
, p. 1196 - 1197 (1997)
alpha-Chymotrypsin-catalyzed transesterification of N-acetyl-L-tyrosine methyl ester in ethanol was markedly accelerated by addition of small amounts of divalent metal salts. The reaction rate dependent not only on the nature of metal ions but also on the nature of anionic counter ions. Calcium acetate was the most effective among the metal salts used. The reaction followed Michaelis-Menten kinetics, and it was found that the reaction increase is due to the increase in kcat.
Tyrosine-Specific Modification via a Dearomatization-Rearomatization Strategy: Access to Azobenzene Functionalized Peptides
Cheng, Yulian,Cheng, Zhehong,Fang, Lijing,Li, Hongchang,Su, Wu,Wang, Pengxin,Wang, Rui,Wu, Chunlei,Zhou, Yimin
supporting information, p. 4137 - 4141 (2021/06/27)
Azobenzene functionalized peptides are of great importance in photoresponsive biosystems and photopharmacology. Herein, we report an efficient approach to prepare azobenzene functionalized peptides through late-stage modification of tyrosine-containing peptides using a dearomatization-rearomatization strategy. This approach shows good chemoselectivity and site selectivity as well as sensitive group tolerance to various peptides. This method enriches the postsynthetic modification toolbox of peptides and has great potential to be applied in medicinal chemistry and chemical biology.
REAGENTS AND PROCESS FOR DIRECT C-H FUNCTIONALIZATION
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Page/Page column 107-108, (2020/06/01)
Thianthrene derivative of the Formula (I): wherein R1 to R8 may be the same or different and are selected from hydrogen, Cl, F, a partially or fully fluorinated C1 to C6 alkyl group, and wherein n is 0 or 1, with the proviso that at least one of R1 to R8 is not hydrogen and process for C-H functionalization of aromatic compounds using this compound.