The solubilization of carotenogenic enzymes of Phycomyces blakesleeanus

The effect of nine ionic and nine non-ionic detergents, over a 0.3–3.0% (w/v) concentration range, on the activity of the enzymes which convert 2-¹⁴C]mevalonic acid into phytoene (7,8,11,12,7′,8′,11′,12′-ψ,ψ-carotene) and β-carotene (β,β-carotene) has been investigated with cell extracts of the C115 carS42 mad-107(?) (β-carotene-accumulating) strain of Phycomyces blakesleeanus. The enzymes catalyzing the conversion of mevalonic acid into phytoene in the C115 and the C5 carB10(?) (phytoene-accumulating) strains of Phycomyces could be released from membranes with high molarity Tris-HCl buffer, but the other carotenogenic enzymes required solubilization with detergents. Enzymic activity was retained with only two ionic detergents (Zwittergents 3–8 and 3–10), whilst Tweens 40 and 60 were the least inhibitory of the non-ionic surfactants. Both Tween 60 and Zwittergent 3–08 solubilized almost 50% of the enzymic activities for the conversion of phytoene to β-carotene, but the former preparation was significantly more stable on storage at ?70°C.