scholarly journals Substrate and Inhibitor Specificities for Human Monoamine Oxidase A and B Are Influenced by a Single Amino Acid

2000 ◽  
Vol 276 (13) ◽  
pp. 9877-9882 ◽  
Author(s):  
Rani Maurice Geha ◽  
Igor Rebrin ◽  
Kevin Chen ◽  
Jean Chen Shih
Keyword(s):  
Amino Acid ◽  
Monoamine Oxidase ◽  
Monoamine Oxidase A ◽  
Single Amino Acid

scholarly journals Monoamine oxidase A from human placenta and monoamine oxidase B from bovine liver both have one FAD per subunit

1989 ◽  
Vol 260 (3) ◽  
pp. 725-729 ◽  
Author(s):  
W Weyler
Keyword(s):  
Amino Acid ◽  
Monoamine Oxidase ◽  
Bovine Liver ◽  
Spectrophotometric Titration ◽  
Monoamine Oxidase A ◽  
Monoamine Oxidase B ◽  
Enzyme Preparations ◽  
Function Mechanism ◽  
Upper Limit ◽  
Quantitative Amino Acid Analysis

I present the first clear evidence that the protein: FAD ratio in human monoamine oxidase A and bovine monoamine oxidase B has an upper limit of 65 kDa and 57 kDa per FAD, respectively. To now it had been assumed that the protein: FAD ratio was 100-120 kDa to 1 FAD and that there was one FAD per two subunits which were assumed to be of the same size. For the present work the purity of monoamine oxidase A and monoamine oxidase B was improved over that previously achieved. Protein was determined by quantitative amino acid analysis and FAD content was measured by spectrophotometric titration of SDS-denatured enzyme with NaS2O4 standardized against riboflavin. The cause of the previous misassignment of the protein: FAD ratio was judged as having been due to the use of impure enzyme preparations. Knowledge of the correct protein: FAD ratio is important in devising cloning strategies for this enzyme, in understanding its structure, function, mechanism, and in the studies of its biosynthesis.

Single Amino Acid Based Self-Assemblies of Cysteine and Methionine

2018 ◽  
Author(s):  
Nidhi Gour ◽  
Bharti Koshti ◽  
Chandra Kanth P. ◽  
Dhruvi Shah ◽  
Vivek Shinh Kshatriya ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Self Assembly ◽  
Aromatic Amino Acids ◽  
Neutral Condition ◽  
Single Amino Acid ◽  
Binding Assays ◽  
Human Neuroblastoma ◽  
Cytotoxicity Assays ◽  
First Time

We report for the very first time self-assembly of Cysteine and Methionine to discrenible strucutres under neutral condition. To get insights into the structure formation, thioflavin T and Congo red binding assays were done which revealed that aggregates may not have amyloid like characteristics. The nature of interactions which lead to such self-assemblies was purported by coincubating assemblies in urea and mercaptoethanol. Further interaction of aggregates with short amyloidogenic dipeptide diphenylalanine (FF) was assessed. While cysteine aggregates completely disrupted FF fibres, methionine albeit triggered fibrillation. The cytotoxicity assays of cysteine and methionine structures were performed on Human Neuroblastoma IMR-32 cells which suggested that aggregates are not cytotoxic in nature and thus, may not have amyloid like etiology. The results presented in the manuscript are striking, since to the best of our knowledge,this is the first report which demonstrates that even non-aromatic amino acids (cysteine and methionine) can undergo spontaneous self-assembly to form ordered aggregates.

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