[Ultrasound velocimetry of lysozyme solutions]

The effects of electrolytes, chemical modifications of amino groups, and inhibitor binding on the hydration and intrinsic compressibility of lysozyme have been studied using precise ultrasound velocity measurements. The interaction of lithium ions with lysozyme accompanied by cooperative decrease of hydration contribution has been revealed. The neutralization of positively charged amino groups due to their modification is shown not only to decrease the hydration of lysozyme but also to increase its intrinsic compressibility. Binding of tri-N-acetylglycosamine to lysozyme is found to induce the 10-15% decrease in globule intrinsic compressibility. The changes observed in intrinsic compressibility of lysozyme correlate with those of its dynamic properties.