Protein or the physical region of the protein that participates in chemical catalysis. In solution proteins also undergo variation in structure through thermal vibration and the collision with other molecules. Proteins can be informally divided into three main classes, which correlate with typical tertiary structures: globular proteins, fibrous proteins, and membrane proteins. Almost all globular proteins are soluble and many are enzymes. Fibrous proteins are often structural, such as collagen, the major component of connective tissue, or keratin, the protein component of hair and nails. Membrane proteins often serve as receptors or provide channels for polar or charged molecules to pass
Skin infection Skin infection Infection of the skin is distinguished from dermatitis, which is inflammation of the skin, but a skin infection can result in skin inflammation. Skin inflammation due to skin infection is called "infective dermatitis." Bacterial skin infections affected about 155 million people and cellulitis occurred in about 600 million people in 2013. Bacterial skin infections include: Fungal skin infections may present as either a superficial or deep infection of the skin, hair, and/or nails. As of 2010, they affect about one billion people globally. Parasitic infestations, stings, and bites in humans are caused by several groups of organisms belonging