Anaerobic lipoxygenase activity fromChlorella pyrenoidosa responsible for the cleavage of the 13-hydroperoxides of linoleic and linolenic acids

Abstract

An enzyme from the alga Chlorella pyrenoidosa, previously identified as a hydroperoxide lyase (HPLS), cleaves the 13‐hydroperoxide derivatives of linoleic and linolenic acids into a volatile C5 fragment and a C13 oxo‐product, 13‐oxo‐9(Z),11(E)tridecadienoic acid (13‐OTA). Gas chromatography/mass spectrometry (GC/MS) headspace analysis of the volatile products indicated the formation of pentane when the substrate was the 13‐hydroperoxide derivative of linoleic acid, whereas a more complex mixture of hydrocarbons was formed when the 13‐hydroperoxide derivative of linolenic acid was the substrate. Analysis of the nonvolatile products by GC/MS and liquid chromatography/mass spectrometry (LC/MS) indicated the formation of 13‐OTA along with the 13‐ketone derivative. This enzymatic activity was inhibited by oxygen but was restored with nitrogen. The enzymatic cleavage activity was coincidental in purified fractions with lipoxygenase activity that produced the 13‐ and 9‐hydroperoxide derivatives of linolenic acid. The results suggest that the enzymatic cleavage activity in Chlorella pyrenoidosa was not a consequence of hydroperoxide lyase activity as previously thought, but was due to anaerobic lipoxygenase activity. This enzyme fraction was purified by (NH4)2 SO4 precipitation, gel filtration, and hydrophobic interaction chromatography. The purified enzyme has an approximate MW of 120 KDa and maximum activity at pH 8.0.

Fatty Acid Hydroperoxide Lyase: A Plant Cytochrome P450 Enzyme Involved in Wound Healing and Pest Resistance

“…Algae ( Chlorella pyrenoidosa and Oscillatoria ) cleave 13‐hydroperoxy fatty acids into 13‐oxo‐(9 Z ,11 E )‐tridecadienoic acid and pentane or (2 Z )‐pentene ( Chlorella ),75 or pentanol ( Oscillatoria ) 76. However, this activity has recently been ascribed to lipoxygenase 77. In mammals, only one HPL has been found (in rabbit leukocytes) 78.…”

A Multifunctional Lipoxygenase with Fatty Acid Hydroperoxide Cleaving Activity from the Moss Physcomitrella patens

“…While higher plants use exclusively polyunsaturated C 18 fatty acids for the production of oxylipins, animals and algae rely predominantly on the transformation of polyunsaturated C 20 fatty acids (3,6), which are not ubiquitously found in the plant kingdom (7). Moreover, the formation of volatile short chain aldehydes relies on the combined action of LOX and HPL species in higher plants, whereas animals and algae seem to be more flexible, because they may use either the LOX/HPL system or specific LOX forms alone (6,8,9). Numerous cDNAs corresponding to LOX have been isolated and characterized from higher plants and animals, but molecular data and mechanistic insight into LOX from other organisms are still scarce (10 -12).…”

Distribution and Role of Oct-1-en-3-ol in Marine Algae

“…Higher plants use exclusively polyunsaturated C 18 FAs for oxylipin production, while animals and algae use predominantly polyunsaturated C 20 FAs [20,23] which are not ubiquitous in the plants [24]. Moreover, the formation of volatile short chain aldehydes relies on LOX and HPL combined action in higher plants, whereas animals and algae seem to be more flexible and may use either LOX/HPL system or specific LOX [23,25]. In general, to produce oxylipins, red algae metabolize C 20 acids via 12-LOX-initiated pathways, green algae metabolize C 18 acids at C-9 and C-13, and brown algae metabolize both C 18 and C 20 acids principally with LOX action at C-6 [23].…”