Soybean lipoxygenase SLO

Although both primary H/T and D/T isotope effects were measured as a function of temperature, the focus of the interpretation was on primary D/T isotope effects, since the smaller commitment for D- than H-transfer leads to a more complete contribution of the chemical step to the measured parameters (see e.g. Section 10.21). The results obtained from this study [92], as well as the earlier work [91], indicate a striking trend in which the value of Ad /At moves from near unity to below unity as the surface of the protein is modified (either by glycosylation or addition of polyethylene glycol). A similar type of pattern has been seen in other enzyme systems, such as the thermophilic ADH [24] (Section 10.5.1.1) and soybean lipoxygenase (SLO) [43] (see Section 10.5.3.1 below) where modification of reaction conditions away from either optimal temperature (ht-ADH) or optimal protein packing (via... 

The observation that LDL may be oxidatively modified by incubation with soybean lipoxygenase (SLO) and phospholipase Ki (Sparrow et al.,... 

The simplest case conceptually is when kcat is fully rate limited by chemistry and, therefore, probes of chemistry (such as isotope effects) are revealed in kcat-This limit is realized in recombinant soybean lipoxygenase-1 (SLO) and its mutants, greatly facilitating the study of C-H cleavage in this enzyme [7-9]. The study of chemistry in this case simply requires that kcat can be faithfully measured as a function of external perturbation, such as temperature, pH, or substrate deut-eration. It is essential to show substrate saturation ([S] Km) under all conditions, however, and this requirement can present experimental limitations. The principal probe for tunneling in enzymes in this kinetic case is the magnitude and temperature dependence of noncompetitive kinetic isotope effects, kcat = kcat(H)/fecat(o)-... 

The enzyme, soybean lipoxygenase-1 (SLO), offers an excellent system in which to illustrate the power of Eq. (10.20) in reproducing experimental data. Several characteristics of SLO are impossible to interpret through a Bell-like tunneling correction. The KIE on k at, k at = 81 + 5, is nearly temperature independent,... 

The formal H-atom abstraction of linoleic acid by soybean lipoxygenase-1 (SLO)... 

Soybean lipoxygenase-1 (SLO) is often used as the prototype for studying the family of lipoxygenases from tissues of different species. They are non-haem iron dioxygenases that catalyse the conversion of unsaturated fatty acids to hydroperoxides. Plant hpoxygenases... 

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