RESUMO
Aldo-keto reductases (AKRs) are responsible for the detoxification of harmful aldehydes. Due to the large number of isotypes, the physiological relevance of AKRs cannot be obtained using mRNA or protein quantification, but only through the use of enzymatic assays to demonstrate functionality. Here, we present a fast and simple protocol to determine the important Michaelis-Menten kinetics of AKRs, which includes various aldehyde substrates of interest such as 4-hydroxynonenal, methylglyoxal, and malondialdehyde. For complete details on the use and execution of this protocol, please refer to Morgenstern et al. (2017) and Schumacher et al. (2018).
Assuntos
Aldo-Ceto Redutases/farmacocinética , Ensaios Enzimáticos/métodos , Enzimas/metabolismo , Aldeído Redutase/química , Aldeído Redutase/genética , Aldo-Ceto Redutases/genética , Aldo-Ceto Redutases/metabolismo , Animais , Cinética , Malondialdeído , Camundongos , Aldeído Pirúvico/metabolismo , Especificidade por SubstratoRESUMO
The glyoxalase system is a highly conserved and ubiquitously expressed enzyme system, which is responsible for the detoxification of methylglyoxal (MG), a spontaneous by-product of energy metabolism. This study is able to show that a phosphorylation of threonine-107 (T107) in the (rate-limiting) Glyoxalase 1 (Glo1) protein, mediated by Ca2+/calmodulin-dependent kinase II delta (CamKIIδ), is associated with elevated catalytic efficiency of Glo1 (lower KM; higher Vmax). Additionally, we observe proteasomal degradation of non-phosphorylated Glo1 via ubiquitination does occur more rapidly as compared with native Glo1. The absence of CamKIIδ is associated with poor detoxification capacity and decreased protein content of Glo1 in a murine CamKIIδ knockout model. Therefore, phosphorylation of T107 in the Glo1 protein by CamKIIδ is a quick and precise mechanism regulating Glo1 activity, which is experimentally linked to an altered Glo1 status in cancer, diabetes, and during aging.
