TCI America Emodin E0500

Emodin / 1,3,8-Trihydroxy-6-methylanthraquinone
In recent years, studies on nitric oxide (NO), one of the reactive oxygen species, have been actively conducted. It is well known that NO is produced in vivo from the guanidino nitrogen of arginine and oxygen by nitric oxide synthase (NOS), and plays an important role in various scenes such as vascular
relaxation, biological defense, neurotransmission modulation and immune system.
The following three types of compounds generate NO.1)
1) Compounds which act on an NO generating system and facilitate NO generation in vivo : e.g. Emodin, etc.
They activate the vascular endothelium and macrophages, etc., increasing NO generation.
2) Compounds which are converted into NO-releasing compounds via metabolism : e.g. nitric esters, nitrite esters, etc.
They react with thiols in vivo and release NO.
3) Compounds which directly release NO by itself : e.g. N-nitrosodiphenylamine, etc.
N-nitrosodiphenylamine releases NO by radical cleavage of the Nï¼NO bond when it is heated to reï¬ ux in benzene.
Popular analytical methods of NO include a chemiluminescent method, a spin trap method and the Griess method.2) The Griess method determines NO2ï¼, which is a metabolite of NO, while the chemiluminescent method and the spin trap method directly determine NO. Moreover, a simultaneous determination method of NO and NO2 using PTIO, the organic radical that selectively oxidizes NO, has been developed.3)

Emodin / 1,3,8-Trihydroxy-6-methylanthraquinone
In this section, proteases are categorized into three modes of actions: (1) serine protease; (2) cysteine protease; (3) metalloprotease.1)
Serine proteases are inhibited by AEBSF, benzamidine, etc.2) Cysteine proteases are inhibited by compounds which react with SH groups such as 2-iodoacetamide or 2-iodoacetic acid.3) Metalloproteases are inhibited by chelating agents, EDTA or 1,10-phenanthroline.4)
In the course of protein extraction, proteolysis is considered to be a major problem because it leads to decreasing yields. Addition of protease inhibitors helps to avoid the proteolysis and improves recovery of the desired protein.5) In the experiment of immunoprecipitation, protease inhibitors are also used to avoid decomposition of antigens or antibodies by proteolytic impurities.6) Protease inhibitors which are frequently used in biochemical research are illustrated in this section.
Thiol protease inhibitors, 2-iodoacetamide and 2-iodoacetic acid, cannot be used in protein extraction, because they form covalent bonds to the SH group of the proteins. In protein research, they are used as an alkylation reagent to derivatize the proteins which are extracted from an electrophoresis gel for mass spectrometric analysis.7)