Insulin crystallization in the presence of basic proteins and peptides

Fullerton, W. Wardle; Low, Barbara W.

doi:10.1016/0005-2795(70)90078-4

Cited by 6 publications

(1 citation statement)

References 10 publications

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“…Known as neutral protamine Hagedorn (NPH) (Hagedorn et al, 1936), these cocrystalline complexes can be prepared identically from wild-type human, beef, or pork insulins because all these insulin forms possess similar self-association properties and readily form hexamers in the presence of zinc (Goldman and Carpenter, 1974;Pekar and Frank, 1972). Unfortunately, crystallographic studies have provided only a low-resolution structure for a wild-type pork insulin complex with clupeine Z, a highly purified form of protamine (Balschmidt et al, 1991;Baker and Dodson, 1970;Simkin et al, 1969;Fullerton and Low, 1970).…”

Section: Introductionmentioning

confidence: 99%

Structural Studies of a Crystalline Insulin Analog Complex with Protamine by Atomic Force Microscopy

Yip

Brader

Frank

et al. 2000

Biophysical Journal

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Crystallographic studies of insulin-protamine complexes, such as neutral protamine Hagedorn (NPH) insulin, have been hampered by high crystal solvent content, small crystal dimensions, and extensive disorder in the protamine molecules. We report herein in situ tapping mode atomic force microscopy (TMAFM) studies of crystalline neutral protamine Lys(B28)Pro(B29) (NPL), a complex of Lys(B28)Pro(B29) insulin, in which the C-terminal prolyl and lysyl residues of human insulin are inverted, and protamine that is used as an intermediate time-action therapy for treating insulin-dependent diabetes. Tapping mode AFM performed at 6 degrees C on bipyramidally tipped tetragonal rod-shaped NPL crystals revealed large micron-sized islands separated by 44-A tall steps. Lattice images obtained by in situ TMAFM phase and height imaging on these islands were consistent with the arrangement of individual insulin-protamine complexes on the P4(1)2(1)2 (110) crystal plane of NPH, based on a low-resolution x-ray diffraction structure of NPH, arguing that the NPH and NPL insulins are isostructural. Superposition of the height and phase images indicated that tip-sample adhesion was larger in the interstices between NPL complexes in the (110) crystal plane than over the individual complexes. These results demonstrate the utility of low-temperature TMAFM height and phase imaging for the structural characterization of biomolecular complexes.

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