Signalling pathways, biotin

A natural extension of these studies would be to identify the pools of proteins in cells and plasma that are nitrosylated (the nitrosylome) via proteomics. Although some advances have been made in this direction with the biotin switch method, where the S-NO is switched to a biotin label (Jaffrey et al, 2001) the technique is plagued by low sensitivity. The identification of the nitrosylome with techniques that allow temporal resolution shorter than signaling frequencies, under physiological and pathological conditions, will be the key to elucidation of the nitrosylation pathway. 

The reaction involves biotin as a carrier of activated HCO3 (Fig. 14-18). The reaction mechanism is shown in Figure 16-16. Pyruvate carboxylase is the first regulatory enzyme in the gluconeogenic pathway, requiring acetyl-CoA as a positive effector. (Acetyl-CoA is produced by fatty acid oxidation (Chapter 17), and its accumulation signals the availability of fatty acids as fuel.) As we shall see in Chapter 16 (see Fig. 16-15), the pyruvate carboxylase reaction can replenish intermediates in another central metabolic pathway, the citric acid cycle. 

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