Figure 1. Mass spectra of CaM T34C/T110C mutant digested by trypsin in-solution or in-gel.

ESI–MS spectra of a tryptically digested T34C/T110C mutant of CaM modified with TG1 represent peptide HVM¹¹⁰CNLGEK from in-solution (A) and from in-gel (B) digests: [M+2H]²⁺ 705.3, 714.3, 698.3 and 707.3 are for cysteine–TG1 P₀, P₁, P₂ and P₃ products respectively (see Scheme 1).