Given two proteins extracted from connective tissue and blood respectively, which structural features would help you identify the connective tissue protein as collagen and the blood protein as hemoglobin?

Collagen shows long, repetitive glycine-proline-hydroxyproline sequences forming a triple-helical fibrous structure that aggregates into fibrils, while hemoglobin is a compact tetrameric globular protein with four noncovalent subunits each containing a heme group.

Collagen forms a compact globular tetramer with heme prosthetic groups for oxygen binding, while hemoglobin forms long rope-like fibrils that give tensile strength to tissues.

Both collagen and hemoglobin are single alpha-helical monomers with identical tertiary folding and no quaternary assembly, so only molecular weight can distinguish them.

Collagen contains many tryptophans that bind oxygen cooperatively whereas hemoglobin contains repeating glycine-proline motifs that form collagen-like triple helices.