Rubber composition and pneumatic tire

The invention relates to a rubber composition comprising a functionalized elastomer having the structure I €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ X-[-S-Z] n (I) where X is a polymer derived from a monomer comprising at least one conjugated diene monomer and optionally at least one vinyl aromatic monomer; S is sulfur; -[-S - Z] is an oligopeptide radical with pendant sulfur S or modified oligopeptide radical with pendant sulfur S, and n is the number of -[-S - Z] groups bonded to X. The invention also relates to a pneumatic tire comprising at least one component, the at least one component comprising a rubber composition, the rubber composition comprising a functionalized elastomer comprising: a polymeric backbone chain derived from a monomer comprising at least one conjugated diene monomer and optionally at least one vinyl aromatic monomer; and a functional group bonded to the backbone chain, the functional group comprising an oligopeptide or modified oligopeptide.