Illustrated Glossary of Organic Chemistry

Lactate dehydrogenase: An enzyme that oxidizes lactate into pyruvate, and reduces pyruvate to lactate. This protein is a tetramer consisting of four identical protein subunits.

Molecular Structure of Lactate Dehydrogenase from the Protein Data Bank
Helix = fuchsia; sheet = yellow; coil = white.

Wire model

Ribbon model