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Metalloporphyrin enzymes and proteins play many roles in terrestrial biochemistry. While their functions and protein structures vary widely, the active site always contains a plate-like porphyrin species (which is not necessarily planar) with various substituents anchored around the ring and a metal ion in the center. In the case of the heme proteins that constitute one of the themes of research at Molecular Research Institute, the porphyrin is protoporphyrin IX and the central ion is iron.

 

Iron-protoporphyrin IX heme from horseradish peroxidase (HRP). Substituents include four methyl, two vinyl, and two propionate groups.

Chlorophyll - the light harvesting engine that powers photosynthesis - is a member of a family that is very closely related to porphyrins and heme proteins. Chlorophyll consists of a reduced porphyrin, known as a chlorin, with a magnesium ion in the center. Chlorins and porphyrins are often very colorful, a fact that provided the title for a recent book by Lionel Milgrom called The Colours of Life.

Walter Kohn and John Pople shared the 1998 Nobel Prize in Chemistry for their contributions to the development of computational chemistry. Click here to go to a page at the official Nobel site that describes how chemistry at the heme site in myoglobin can be studied computationally.