Myrosinase
| Myrosinase ( Sinapis alba ) | ||
|---|---|---|
| Mass / length primary structure | 501 amino acids | |
| Secondary to quaternary structure | Homodimer | |
| Cofactor | Ascorbate, zinc | |
| Identifier | ||
| External IDs | ||
| Enzyme classification | ||
| EC, category | 3.2.1.147 , glycosidase | |
| Response type | hydrolysis | |
| Substrate | Thioglucoside + H 2 O | |
| Products | Sugar + thiol | |
| Occurrence | ||
| Parent taxon | plants | |
The myrosinase (also Sinigrinase or thioglucosidase ) (from gr. Myron = ointment , ointment , balm and green. Sinapi = mustard ) is an enzyme of plant origin, the glucosinolates into glucose ( dextrose splits) and mustard oils. In this way, the plant defends itself against predators , because mustard oils generally have a pungent smell or taste. The mustard oil glycoside therefore represents the harmless and therefore storable precursor of these aggressive substances.
Myrosinase comes predominantly in crucifers (Brassicaceae), such as in mustard , Brussels sprouts , and radish as well as in capers plants (Capparaceae) as the Kaper before, which are distinguished because of the occurring in them glucosinolates by a sharp taste. In the plant, myrosinase and its substrates (mustard oil glycosides) are stored separately in different cells. Only when the plant is damaged, for example by the mouthparts of an insect, do the two components mix. The myrosinase now splits the mustard oil glycosides, so that mustard oils are produced. Mustard oils include isothiocyanates (such as allyl mustard oil ), thiocyanates, nitriles and epithionitriles. Some of these substances are highly volatile and have a pungent smell, others are non-volatile and have a pungent taste. Together they serve to ward off predators such as herbivorous insects. Some plants, for example. Kohl , accelerate the myrosinase reaction by incorporation of vitamin C . In fact, cabbage has a higher vitamin C content than oranges .
The reaction of myrosinase is used by humans to flavor dishes. If horseradish is rubbed, the storage cells of myrosinase and mustard oil glycoside are damaged, so that both components come together and mustard oils are created, which produce the characteristic sharp taste. If, on the other hand, the horseradish is cooked, no tissue damage occurs, so that it is not spicy.
Individual evidence
- ^ Wissenschaft-Online-Lexika: Entry on myrosinase in the Lexikon der Biologie , accessed March 4, 2008