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Open access, freely available online Synopses of Research Articles Simple Peptides Stabilize Mighty Membrane Proteins for Study DOI: 10.1371/journal.pbio.0030259 Cell membranes are largely made stabilize the dauntingly large protein of proteins, and membrane proteins complex photosystem I (PS-I), an integral account for about a third of all genes. part of the photosynthetic machinery. Despite their importance, they are The molecule they made, abbreviated devilishly hard to isolate and stabilize, A6 K, links six units of the hydrophobic and therefore are hard to study. The amino acid alanine to one of the problem lies in their structure: membrane hydrophilic amino acid lysine. The proteins have at least one hydrophobic authors used it to stabilize PS-I and then DOI: 10.1371/journal.pbio.0030259.g001 domain, composed of a stretch of water- attached the detergent–protein complex The designed short peptide (protein repelling amino acids, which holds the to a glass slide, allowed it to dry, and fragment) detergents look like matches and protein snugly in the lipid membrane. examined the stability of PS-I by testing behave like lipids or oil molecules that repel Purifying such a protein in an aqueous its fl uorescence. Intact PS-I emits red light water at one end but at