Introduction

DeLucas, L.J.

doi:10.1016/s1063-5823(09)63024-6

Cited by 1 publication

(2 citation statements)

References 16 publications

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“…The most attractive hypothesis that comes to mind (indeed, there may be others) is based on analogy with another molecular structural combination with which we are familiar; that is, detergent-membrane protein complex crystals. In these crystals detergent makes up a very large proportion of the crystal (DeLucas, 2009;Loll, 2003;Michel, 1991;Wiener, 2004;Zulauf, 1990) and more or less fills interstitial spaces along with solvent. The detergent, however, is never, or at least seldom, visualized in electron-density maps.…”

Section: Discussionmentioning

confidence: 99%

“…The dyes, with their large hydrophobic cores and solubilizing hydrophilic groups, may be acting as detergents that surround exposed hydrophobic patches on the exterior of protein molecules. Indeed, it is well known that detergents that are bound in this way are often difficult to remove or replace even by extensive dialysis (DeLucas, 2009;Loll, 2003;Michel, 1991;Wiener, 2004;Zulauf, 1990), as are the dyes. In addition, Difference electron density is shown superimposed on a molecule of xylene cyanol that lies exactly on a crystallographic twofold axis at a position different from that where the thioflavin T dimer is bound.…”

Section: Discussionmentioning

confidence: 99%

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Investigation into the binding of dyes within protein crystals

McPherson

Larson

2018

Acta Cryst Sect F

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It was found that the crystals of at least a dozen different proteins could be thoroughly stained to an intense color with a panel of dyes. Many, if not most, of the stained protein crystals retained the dyes almost indefinitely when placed in large volumes of dye-free mother liquor. Dialysis experiments showed that most of the dyes that were retained in crystals also bound to the protein when free in solution; less frequently, some dyes bound only in the crystal. The experiments indicated a strong association of the dyes with the proteins. Four protein crystals were investigated by X-ray diffraction to ascertain the mode of binding. These were crystals of lysozyme, thaumatin, trypsin inhibited with benzamidine and satellite tobacco mosaic virus. In 30 X-ray analyses of protein crystal-dye complexes, in only three difference Fourier maps was any difference electron density present that was consistent with the binding of dye molecules, and even in these three cases (thaumatin plus thioflavin T, xylene cyanol and m-cresol purple) the amount of dye observed was inadequate to explain the intense color of the crystals. It was concluded that the dye molecules, which are clearly inside the crystals, are disordered but are paradoxically tightly bound to the protein. It is speculated that the dyes, which exhibit large hydrophobic cores and peripheral charged groups, may interact with the crystalline proteins in the manner of conventional detergents.

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Section: Discussionmentioning

confidence: 99%