A method of producing a variant glycolipid acyltransferase enzyme comprising: (a) selecting a parent enzyme which is a lipid acyltransferase enzyme characterised in that the enzyme comprises the amino acid sequence motif GDSX, wherein X is one or more of the following amino acid residues L, A, V, I, F, Y, H, Q, T, N, M or S; (b) modifying one or more amino acids to produce a variant lipid acyltransferase; (c) testing the variant lipid acyltransferase for transferase activity, and optionally hydrolytic activity, on a galactolipid substrate, and optionally a phospholipid substrate and/or optionally a triglyceride substrate; (d) selecting a variant enzyme with an enhanced activity towards galactolipids compared with the parent enzyme; and optionally (e) preparing a quantity of the variant enzyme; wherein the method further comprises one or more of the following steps: structural homology mapping or sequence homology alignment; wherein the structural homology mapping comprises one or more of the following steps: (a) aligning a parent sequence with a structural model of the amino acid sequence SEQ ID No. 2 obtained by structural alignment of the crystal structure co-ordinates of SEQ ID No. 2 with 1IVN.PDB shown in figure 52 (b) selecting one or more amino acids within a 10Å sphere centred on the central carbon atom of the glycerol molecule in the active site; (c) determining if one or more amino acid residues selected in accordance with step (b) are highly conserved; and (d) modifying one or more amino acids selected in accordance with step (b), excluding conserved regions identified in accordance with step (c) in said parent sequence; and wherein the sequence homology alignment comprises one or more of the following steps: (i) selecting a first parent lipid acyltransferase; (ii) identifying a second related lipid acyltransferase having a desirable activity; (iii) aligning said first parent lipid acyltransferase and the second related lipid acyltransferase; (iv) identifying amino acid residues that differ between the two sequences; (v) determining if one or more amino acid residues selected in accordance with step (iv) are highly conserved; and (vi) modifying one or more of the amino acid residues identified in accordance with step (iv) excluding conserved regions identified in accordance with step (v) in said parent sequence, and wherein the following amino acid residues identified by alignment with SEQ ID No. 2 is modified compared with a parent sequence: S18 M or T; Y30 G, I, L, S, E, M, A or R; G40 L, R, M, Q or V; N80 R, D, P G or E; N87 R, D, E, M, C or G; N88W; Y179 V, E, R, N or Q; H180, T, K, Q or I; M209 Y, L, K or M; L210 N, D, H, R, E, A, Q, P, K, G, T, W, I, V, S or M; R211 G, Q, K, D or T; N215 H, L, G, V, R, or Y. (a) aligning a parent sequence with a structural model of the amino acid sequence SEQ ID No. 2 obtained by structural alignment of the crystal structure co-ordinates of SEQ ID No. 2 with 1IVN.PDB shown in figure 52 (b) selecting one or more amino acids within a 10Å sphere centred on the central carbon atom of the glycerol molecule in the active site; (c) determining if one or more amino acid residues selected in accordance with step (b) are highly conserved; and (d) modifying one or more amino acids selected in accordance with step (b), excluding conserved regions identified in accordance with step (c) in said parent sequence; (i) selecting a first parent lipid acyltransferase; (ii) identifying a second related lipid acyltransferase having a desirable activity; (iii) aligning said first parent lipid acyltransferase and the second related lipid acyltransferase; (iv) identifying amino acid residues that differ between the two sequences; (v) determining if one or more amino acid residues selected in accordance with step (iv) are highly conserved; and (vi) modifying one or more of the amino acid residues identified in accordance with step (iv) excluding conserved regions identified in accordance with step (v) in said parent sequence,