Sandbox Reserved 191: Difference between revisions
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The binding surface of PPT-1 creates an external hydrophobic groove that binds the palmitate acid in-between carbon 4 and 5 (Figure 1). The acid binds in a [https://en.wikipedia.org/wiki/Gauche_effect gauche conformation] creating a <scene name='58/580839/Kink_in_acid/1'>kink </scene> | The binding surface of PPT-1 creates an external hydrophobic groove that binds the palmitate acid in-between carbon 4 and 5 (Figure 1). The acid binds in a [https://en.wikipedia.org/wiki/Gauche_effect gauche conformation] creating a <scene name='58/580839/Kink_in_acid/1'>kink </scene> | ||
in the acid chain. This bending suggests that PPT-1 was originally designed to react with an unsaturated fatty acid with cis-double bonds. The catalytic <scene name='43/436866/Triad_w_zoom_no_backbones/1'>triad</scene> is composed of Serine-115, Aspartate-233, and Histidine-289 <ref name="mutations" />. Ser-115 is deprotonated by His-289 and attacks the carbonyl carbon of the thioester bond connecting palmitic acid to the protein substrate. The negative charge is pushed onto the oxygen and is stabilized by in an oxyanion hole a water molecule. The tetrahedral intermediate collapses and kicks the palmatic acid off of the cysteine residue<ref name="mutations" />. | in the acid chain. This bending suggests that PPT-1 was originally designed to react with an unsaturated fatty acid with cis-double bonds. The catalytic <scene name='43/436866/Triad_w_zoom_no_backbones/1'>triad</scene> is composed of Serine-115, Aspartate-233, and Histidine-289 <ref name="mutations" />. Ser-115 is deprotonated by His-289 and attacks the carbonyl carbon of the thioester bond connecting palmitic acid to the protein substrate. The negative charge is pushed onto the oxygen and is stabilized by in an oxyanion hole a water molecule. The tetrahedral intermediate collapses and kicks the palmatic acid off of the cysteine residue<ref name="mutations" />. | ||
[[Image: | [[Image:Rxn ppt1.jpg|400px|right|thumb|Figure 2: The basic enzymatic reaction catalyzed by PPT-1. Ser-115, depronated by His-289, attacks the carbonyl carbon of the thioester bond ]] | ||