The calphostins are a class of closely related chemical compounds isolated from the fungus Cladosporium cladosporioides

Cladosporium cladosporioides

Cladosporium cladosporioides is a fungal plant pathogen that affects wheat. It is the source of the series of chemical compounds known as calphostins.- External links :* *...

. The known calphostins include calphostin A, calphostin B, calphostin C, calphostin D, and calphostin I. The calphostins are inhibitors

Enzyme inhibitor

An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...

 of protein kinase C

Protein kinase C

Protein kinase C also known as PKC is a family of enzymes that are involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins. PKC enzymes in turn are activated by signals such as increases in...

 (PKC). The most potent member of the series, calphostin C, has found use as a biochemical tool because of this activity.

Calpohostin	R1	R2
Calphostin A	Bz	Bz
Calphostin B	Bz	H
Calphostin C	Bz	4-(HO)Bz
Calphostin D	H	H
Calphostin I	4-(HO)Bz	4-(HO)Bz

Calphostin C

Calphostin C is a potent inhibitor

Enzyme inhibitor

An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...

 of protein kinase C

Protein kinase C

Protein kinase C also known as PKC is a family of enzymes that are involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins. PKC enzymes in turn are activated by signals such as increases in...

(PKC).