This document discusses enzyme cofactors and metalloporphyrins. It outlines various ion cofactors like copper, iron, magnesium, and zinc and the enzymes they are involved in. It also mentions iron-sulfur proteins and their role in electron transfer reactions in the mitochondrial respiratory chain. Additionally, it describes metalloporphyrins like heme and chlorophyll, noting heme is involved in oxygen transport and chlorophyll in photosynthesis. The document also provides details on cobalamin (vitamin B12), describing its complex chemical structure and roles in cytoplasmic methylation reactions and mitochondrial methylmalonyl-CoA mutase.

1. ENZYMES -3
ENZYME COFACTORS
-------COENZYMES
DR RINA DAS MEHTA
MMCP, MULLANA

2. IONS AS A COFACTORS
Ion Examples of enzymes containing this ion
Cu2+ Cytochromoxidase, catalase
Fe2+ a Fe3+ Cytochroms, hydroxylases
Mg2+ Glucose-6-phosphatase, hexokinase, DNA-
polymerase,
Mn2+ Arginase
Zn2+ Alcohol dehydrogenase, DNA polymerase,
carboanhydrase
Se Glutathionperoxidase
FeS proteins (Fe2S2) NADH dehydrogenase, succinate dehydrogenase

3. FERREDOXINS
• FES PROTEINS – FERREDOXINS - FE2S2, FE4S4 ELECTRON
TRANSFER :
• REDOX REACTION IN MITOCHONDRIAL RESPIRATORY CHAIN
(COMPLEX I AND COMPLEX II)
• NADH DEHYDRODENASE, KOENZYM Q - CYTOCHROM C
REDUCTASE, SUCCINATE – KOENZYM Q REDUCTASE

4. METALLOPORPHYRINS - HEME
• ORGANIC, CYCLIC COMPOUNDS
DERIVED FROM THE TETRAPYRROLE
- PORPHYRIN - FOUR PYRROL RINGS
ARE LINKED WITH METHYLENE
BRIDGES.
• COMPLEXES WITH METAL IONS
• HEME – FE, OXYGENE
TRANSPORT
• CHLOROPHYL – MG,
PHOTOSYNTHESIS

5. METALLOPORPHYRINS -
COBALAMIN (VITAMIN B12)
• CHEMICALLY MOST COMPLEX
VITAMIN
• STRUCTURALLY SIMILAR TO
HEME - COMPLEX OF ORGANIC
COMPOUNDS, ATOM WITHIN
THE MOLECULE IS CO,
• IN MAN THERE ARE TWO
METABOLICALLY ACTIVE FORMS:
METHYLKOBALAMIN AND
ADENOSYLKOBALAMIN.
• COBALAMIN CATALYSES TWO
REACTIONS
• CYTOPLASMIC
METHYLATION OF
HOMOCYSTEIN TO
METHIONIN.
• MITOCHONDRIAL
METHYLMALONYL-COA
MUTASE (METHYLMALONYL-
COA → SUKCYNYL-COA)
NEEDS DEOXY