Interestingly, we did find evidence for S‐nitrosylation at cysteine 93 of mitochondrial MDH in control and AD human brains (Figure 1A and Table S1, Supporting Information, EXCEL spreadsheet 6, labeled “Shared Proteins and Sites,” line 184); note, however, in AD human brains, S‐nitrosylation at cysteine 93 decreased, and a new site at cysteine 212 was detected (Table S1, Supporting Information, EXCEL spreadsheet 8, labeled “Shared Proteins New Sites,” line 20; spreadsheet 10, labeled “Shared Sites p < 0.05,” line 10; spreadsheet 11, labeled “TCA Enzymes,” line 17). Here, MDH2 is linked to Alzheimer disease.