The effects of acrylamide on brain creatine kinase: Inhibition kinetics and computational docking simulation

Comparative study of aluminum speciation on brain-type creatine kinase: Enzyme kinetic, molecular docking, cellular experiment, and mouse model study

Brain-type Creatine kinase (CK-BB), which has a high affinity for Aluminum (Al), and its abnormality is closely related to neurodegenerative diseases. In this study, the comparative effect of Al speciation on the bioactivity of CK-BB has been studied by the inhibition kinetics method, molecular docking, cellular experiment, and mouse model study. Results showed that the half-inhibitory concentration of AlCl₃ was 0.67 mM, while Al(mal)₃ was 3.81 mM. Fluorescence spectra showed that Al(mal)₃ had a more substantial effect on the endogenous fluorescence of CK-BB than AlCl₃. Molecular docking showed that AlCl₃ was closer to the active site of CK-BB. C6 cells were used to explore the enzyme activity and intracellular distribution of CK-BB by AlCl₃ or Al(mal)₃. AlCl₃ treatment may directly affect CK-BB activity and cause insufficient local ATP supply in cells which affected the formation of F-actin and cell morphology. The change in the hydrophobicity of CK-BB induced by Al(mal)₃ affected the movement of CK-BB, which subsequently activated thecytochrome C (Cyt C)/Caspase 9/Caspase 3 pathway. Similar results have been found in vivo experiments. This study demonstrated that interaction between Al and CK-BB might be related to the process of Al-induced energy metabolism disorders, in which the Al speciation revealed differentiated toxicity mechanisms.

Molecular determinants of acrylamide neurotoxicity through covalent docking

Acrylamide (ACR) is formed during food processing by Maillard reaction between sugars and proteins at high temperatures. It is also used in many industries, from water waste treatment to manufacture of paper, fabrics, dyes and cosmetics. Unfortunately, cumulative exposure to acrylamide, either from diet or at the workplace, may result in neurotoxicity. Such adverse effects arise from covalent adducts formed between acrylamide and cysteine residues of several neuronal proteins via a Michael addition reaction. The molecular determinants of acrylamide reactivity and its impact on protein function are not completely understood. Here we have compiled a list of acrylamide protein targets reported so far in the literature in connection with neurotoxicity and performed a systematic covalent docking study. Our results indicate that acrylamide binding to cysteine is favored in the presence of nearby positively charged amino acids, such as lysines and arginines. For proteins with more than one reactive Cys, docking scores were able to discriminate between the primary ACR modification site and secondary sites modified only at high ACR concentrations. Therefore, docking scores emerge as a potential filter to predict Cys reactivity against acrylamide. Inspection of the ACR-protein complex structures provides insights into the putative functional consequences of ACR modification, especially for non-enzyme proteins. Based on our study, covalent docking is a promising computational tool to predict other potential protein targets mediating acrylamide neurotoxicity.

Effects of acrylamide on the activity and structure of human brain creatine kinase

Acrylamide is widely used worldwide in industry and it can also be produced by the cooking and processing of foods. It is harmful to human beings, and human brain CK (HBCK) has been proposed to be one of the important targets of acrylamide. In this research, we studied the effects of acrylamide on HBCK activity, structure and the potential binding sites. Compared to CKs from rabbit, HBCK was fully inactivated at several-fold lower concentrations of acrylamide, and exhibited distinct properties upon acrylamide-induced inactivation and structural changes. The binding sites of acrylamide were located at the cleft between the N- and C-terminal domains of CK, and Glu232 was one of the key binding residues. The effects of acrylamide on CK were proposed to be isoenzyme- and species-specific, and the underlying molecular mechanisms were discussed.