title: gamma-Zein secondary structure in solution by circular dichroism.
abstract: The proline-rich N-terminal domain of gamma-zein has been reported in relevant processes, which include its ability to cross the cell membranes. Evidences indicate that synthetic hexapeptide (PPPVHL), naturally found in N-terminal portion of gamma-zein, can adopt the polyproline II (PPII) conformation in aqueous solution. The secondary structure of gamma-zein in maize protein bodies had been analyzed by solid state Fourier transform infrared and nuclear magnetic resonance spectroscopies. However, it was not possible to measure PPII content in physiological environment since the beta-sheet and PPII signals overlap in both solid state techniques. Here, the secondary structure of gamma-zein has been analyzed by circular dichroism in SDS aqueous solution with and without ditiothreitol (DTT), and in 60% of 2-propanol and water with DTT. The results show that gamma-zein has high helical content in all solutions. The PPII conformation was present at about 7% only in water/DTT solution.
authors.affiliation: Universidade de São Paulo, Instituto de Química de São Carlos, Av. Trabalhador Sãocarlense, 400, São Carlos, SP 13560-970, Brazil.
authors.forename: Tatiana C
authors.initials: TC
authors.lastname: Bicudo
authors.forename: Rogério C
authors.initials: RC
authors.lastname: Bicudo
authors.forename: Lucimara A
authors.initials: LA
authors.lastname: Forato
authors.forename: Leila M
authors.initials: LM
authors.lastname: Beltramini
authors.forename: Luiz A R
authors.initials: LA
authors.lastname: Batista
authors.forename: Rubens Bernardes
authors.initials: RB
authors.lastname: Filho
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Colnago
mesh_terms: D020816:Amino Acid Motifs; D002942:Circular Dichroism / Q000379:methods; D004229:Dithiothreitol / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010455:Peptides / Q000737:chemistry; D011392:Proline; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D003313:Zea mays / Q000737:chemistry* / Q000145:classification; D015028:Zein / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D010455:Peptides; D012996:Solutions; C011083:polyproline; D012967:Sodium Dodecyl Sulfate; D015028:Zein; D011392:Proline; D004229:Dithiothreitol