heme
The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.
DEFINITION:
- heme
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1. The nonprotein, ferrous-iron-containing component of hemoglobin, having composition C34H32FeN4O4.
2. Any quadridentate chelate of iron with the four pyrrole groups of a porphyrin, further distinguished as ferroheme or ferriheme referring to the chelates of Fe(II) and Fe(III) respectively. The four porphyrin ligands form a square-planar complex; the fifth and sixth coordination positions of the iron atom are perpendicular to the plane of the porphyrin and both may be occupied by strong field ligands, such as a nitrogen atom of a histidine residue of a protein, as in cytochromes, or only one may be so occupied, as in hemoglobin where the sixth position reversibly binds oxygen.
3. Ferroheme, the Fe(II) chelate; See also hematin .
4. Protoheme IX, the heme of hemoglobin.
Used in 10 Term definitions
Used in 10 Term definitions