label: a 1-tetracosanoyl-2-acyl-phosphoglycerolipid + 2 Fe(II)-[cytochrome b5] + O2 + 2 H(+) => a 1-[(15Z)-tetracos-15-enoyl]-2-acyl-phosphoglycerolipid + 2 Fe(III)-[cytochrome b5] + 2 H2O
label_lc: a 1-tetracosanoyl-2-acyl-phosphoglycerolipid + 2 fe(ii)-[cytochrome b5] + o2 + 2 h(+) => a 1-[(15z)-tetracos-15-enoyl]-2-acyl-phosphoglycerolipid + 2 fe(iii)-[cytochrome b5] + 2 h2o