A key component of body odour is the volatile thioalcohol, 3-methyl-3-sulfanylhexan-1-ol (3M3SH). The structure may be visualized as hexan-1-ol "substituted by a methyl group and a thiol group at position 3 " (pubchem)
A major contributor to the formation of 3M3SH is the commensal bacterium, Staphylococcus hominis, which produces it as a by-product of the metabolism of (odourless) Cys-Gly-3M3SH.
Cys-Gly-3M3SH, "an L-cysteinylglycine dipeptide-conjugated alcohol that is secreted onto the surface of the skin by apocrine glands" (Ref 2), is itself produced as a by-product of human metabolism in sweat glands.
The key enzyme is a cysteine-thiol lyase (C-T lyase), which (among many other interesting attributes), contains pyridoxal phosphate.
Ref 1: Structural basis of malodour precursor transport in the human axilla (Minhas et al., 2018)
Ref 2: The molecular basis of thioalcohol production in human body odour (Rudden et al., 2020; Nature (Scientific Reports))
Ref 3: Know sweat: scientists solve mystery behind body odour (The Guardian, July 2020)
Ref 4: Structure of 3M3SH at pubchem.