User:Anna Postnikova/MAT
From Proteopedia
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== Active Site Mechanism == | == Active Site Mechanism == | ||
| - | ATP and methionine are stabilized in the active site by the residues present there, including lysine and histidine | + | ATP and methionine are stabilized in the active site by the residues present there, including lysine and histidine. The slightly negative sulfur atom of methionine undergoes a nucleophilic attack on the slightly positive 5th carbon of the adenosine sugar unit. Following this, the bond from the 5th carbon to the oxygen breaks, separating the three phosphates from the newly formed S-adenosylmethionine (SAM) <ref name="Murray et al.">Murray B, Antonyuk SV, Marina A, Lu SC, Mato JM, Hasnain SS, Rojas Al. Crystallography captures catalytic steps in human methionine adenosyltransferase enzymes. PNAS. 2016 Feb 8;113 (8) 2104-2109. doi: https://doi.org/10.1073/pnas.1510959113</ref>. This is an example of an SN2 reaction, where an intermediate forms as the substrates are transitioning to their product forms. The product is only released after the methionine binds and the C-O bond breaks. |
== Structure == | == Structure == | ||
Revision as of 14:38, 6 April 2022
Contents |
Methionine adenosyltransferase
Methionine adenosyltransferase (MAT) synthesizes S-adenosylmethionine from the substrates adenosine triphosphate (ATP) and methionine. ATP isn’t used as a source of energy like it is in other reactions but gets a methionine added onto the 5th carbon while the three phosphate groups are broken down and released from the active site. This enzyme is conserved and found in many organisms, so it is essential for life. Problems with this enzyme have been shown to cause diseases such as various cancers.
SAM Formation Mechanism
Active Site Mechanism
ATP and methionine are stabilized in the active site by the residues present there, including lysine and histidine. The slightly negative sulfur atom of methionine undergoes a nucleophilic attack on the slightly positive 5th carbon of the adenosine sugar unit. Following this, the bond from the 5th carbon to the oxygen breaks, separating the three phosphates from the newly formed S-adenosylmethionine (SAM) [1]. This is an example of an SN2 reaction, where an intermediate forms as the substrates are transitioning to their product forms. The product is only released after the methionine binds and the C-O bond breaks.
Structure
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References
- ↑ 1.0 1.1 Murray B, Antonyuk SV, Marina A, Lu SC, Mato JM, Hasnain SS, Rojas Al. Crystallography captures catalytic steps in human methionine adenosyltransferase enzymes. PNAS. 2016 Feb 8;113 (8) 2104-2109. doi: https://doi.org/10.1073/pnas.1510959113
