The difference between glycocapsule and glycoprotein

Many people cannot distinguish the names of some things, because one thing may have several names, and even many elements have different names. So people often cannot tell the difference between sugar quilt and sugar. First of all, the difference is not too big. It depends on each person's understanding and knowledge. Many people will have questions about this and want to understand its role and effect.

Glycocalyx is a layer of transparent gelatinous substance of variable thickness that covers the cell wall of some bacteria. The presence and thickness of the sugar coat are not only related to the genetics of the strain, but also closely related to the environment, especially the nutritional conditions. Depending on whether they have fixed layers and the thickness of the layers, the glycocapsule can be further divided into several types, such as capsule (or macrocapsule), microcapsule, slime layer and zoogloea.

The capsule has a high water content and can be seen under a light microscope after dehydration and special staining. In the laboratory, if carbon black ink is used to negatively stain capsule-producing bacteria (i.e., background staining), the capsule can also be easily observed under a light microscope, while the mucus layer does not have this feature.

The components of the glycosides are generally polysaccharides, a few are proteins or polypeptides, and there are also complexes of polysaccharides and polypeptides. For example, Xanthobacter species have both a capsule containing α-polyglutamine and a mucus layer containing a large amount of polysaccharides. This slime layer cannot be precipitated by centrifugation, and sometimes even when the liquid culture container is inverted, the entire gel-like culture (culture, the general term for bacteria and culture fluid) will not flow out.

Introduction

Glycoprotein is a complex carbohydrate composed of branched oligosaccharide chains covalently linked to polypeptide chains. The main chain is shorter and, in most cases, the sugar content is lower than that of protein. In glycoproteins, the composition of sugars is often complex, including mannose, galactose, fucose, glucosamine, galactosamine, sialic acid, etc.

Oligosaccharides and proteins can be bound in two ways: (1) the hemiacetal hydroxyl group of the sugar and the hydroxyl-containing amino acids (serine, threonine, hydroxylysine, etc.) are bound by an O-glycosidic bond; (2) the hemiacetal hydroxyl group of the sugar and the amide group of asparagine are bound by an N-glycosidic bond. It is widely distributed in nature. Of the sixty or seventy plasma proteins that have been studied, the vast majority are glycoproteins. Some enzymes and hormones are glycoproteins. Glycoproteins are also important components of cell membranes, extracellular matrix, plasma mucus, etc. An increasing number of glycoproteins, especially lectins, are isolated from plants.

A variety of lectins have been isolated from vertebrates, invertebrates, and even many microorganisms, most of which are glycoproteins. Glycoproteins are species-specific; a protein exists as a glycoprotein in one animal but not in another.