The target substrates are polyphosphates which are known to be the natural substrates of alkaline phosphatase [ 21].
The specificity of LacY stems from targeting the galactopyranosyl ring of lactose, which is the natural substrate.
The studies on the acceptor substrate specificity of the enzyme, α3GalT, show that in addition to LacNAc, which is the natural substrate, the enzyme accepts various other disaccharides as substrates such as lactose and Gal derivatives, β-O-methylgalactose and β-D-thiogalactopyranoside, albeit with lower specific activities.
The hemimethylated substrate has the added advantage of being the natural substrate for the enzyme during DNA replication [26].
Of note, L-Arginine, but not D-arginine, is the natural substrate for nitric oxide synthase (NOS).
On one hand, a phsA disruption mutant accumulated AcDMPT, suggesting that this compound is the natural substrate (14, 15).
At the other extreme is UFT including uracil (U) which is a simple competitive inhibitor of DPD activity since it is the natural substrate of DPD.
The magnitude of the kinetic constants and activities of put PtMVD with MVA were similar to those of ScMVD with MVAPP, consistent with the hypothesis that MVA is the natural substrate of put PtMVD, as MVAPP is for ScMVD.
However, water is the natural substrate for these enzymes, and this complicates the study of hydrolase-catalyzed reactions; that is to say, they are not ideal systems for investigating the influence of water on the activity and selectivity of enzymes.
(i) The most reactive anomeric hydroxy group in sugars can be selectively oxidised by a range of well-studied oxidases (Scheme 12): d-Glucose (Table 7, entry 1) is the natural substrate of the flavoenzyme GOX [EC 1.1.3.4], well studied from Aspergillus niger, which displayed a very narrow substrate spectrum and oxidises glucose at the C1 position (Nakamura and Ogura 1968).
