biostudies-literatureBrady NGUniversity of Tennessee, KnoxvilleOffice of CyberinfrastructureDivision of Molecular and Cellular BiosciencesOffice of Experimental Program to Stimulate Competitive ResearchOak Ridge National LaboratoryDivision of Graduate Education31781-31796https://www.ebi.ac.uk/biostudies/studies/S-EPMC9072662biostudies-literatureUnknown9(54)Photosystem I (PSI) from the thermophilic cyanobacterium <i>Thermosynechococcus elongatus</i> (Te) is the largest membrane protein complex to have had its structure solved by X-ray diffraction. This trimeric complex has 36 protein subunits, over 380 non-covalently bound cofactors and a molecular weight of ∼1.2 MDa. Previously, it has been isolated and characterized in a detergent micelle using the non-ionic detergent <i>n</i>-dodecyl-β-d-maltoside (DDM). We have now succeeded in isolating this complex without the use of detergents, using styrene-maleic acid (SMA) alternating copolymer. Intriguingly, a partially esterified copolymer formulation (SMA 1440, Cray Valley) was found to be most efficient in cyanobacterial thylakoid membranes. A host of biochemical, biophysical and functional assaRSC advancesNon-detergent isolation of a cyanobacterial photosystem I using styrene maleic acid alternating copolymers.PMC9072662EPS-1004083DGE-0801470MCB-1452464OCI-1053575Gumbart JCBrady NGBruce BDMa YLi MfalseNon-detergent isolation of a cyanobacterial photosystem I using styrene maleic acid alternating copolymers.Photosystem I (PSI) from the thermophilic cyanobacterium <i>Thermosynechococcus elongatus</i> (Te) is the largest membrane protein complex to have had its structure solved by X-ray diffraction. This trimeric complex has 36 protein subunits, over 380 non-covalently bound cofactors and a molecular weight of ∼1.2 MDa. Previously, it has been isolated and characterized in a detergent micelle using the non-ionic detergent <i>n</i>-dodecyl-β-d-maltoside (DDM). We have now succeeded in isolating this complex without the use of detergents, using styrene-maleic acid (SMA) alternating copolymer. Intriguingly, a partially esterified copolymer formulation (SMA 1440, Cray Valley) was found to be most efficient in cyanobacterial thylakoid membranes. A host of biochemical, biophysical and functional assa2019-01-01T00:00:00Z2019 Oct2025-04-18T12:13:16.841Z2025-04-06T21:51:51.095ZS-EPMC90726623552792010.1039/c9ra04619d