Lectin plant and comprises two protein domains. Abrin from the jequirity pea is similar: Lectins are ubiquitous in nature and many foods contain the proteins. Because some lectins can be harmful if poorly cooked or consumed in great quantities, "lectin-free" fad diets have been proposed, most based on the writing of Steven Gundry. A typical lectin-free diet excludes a range of foods, including most grains, pulses and legumes, as well as eggs, seafood and many staple fruits and vegetables. These foods do not contain harmful levels of lectins when properly cooked, and there is no health benefit to following these diets
Beta-keratin whose flight capabilities have been questioned, would have had avian, but not feather, β-keratins. The small alvarezsaurid dinosaur "Shuvuuia deserti" shows evidence of a featherlike skin covering. Analysis by Schweitzer "et al." (1999) showed that these featherlike structures consisted of beta-keratin. There are two main forms of keratin, alpha-keratin and beta-keratin. Alpha-keratin is seen in humans and other mammals, beta-keratin is present in birds and reptiles. Beta-keratin is harder than alpha-keratin. Structurally alpha-keratin have alpha-helical coiled coil structure while beta-keratin have twisted beta sheet structure.bIn the case of β-sheets, this allows sterically-unhindered hydrogen bonding between the amino and carboxyl groups