Protein Structure — Primary to Quaternary

A 28-year-old Indian male presents to the emergency department with acute onset severe chest pain and shortness of breath. He has a family history of sudden cardiac death in his father at age 35. On examination, he has a tall stature, lens dislocation noted on ophthalmologic examination, and arachnodactyly. Echocardiography reveals aortic root dilatation with aortic regurgitation. Genetic testing confirms a mutation in the FBN1 gene encoding fibrillin-1. Which level of protein structure is primarily disrupted in this condition?

A 35-year-old Indian female presents with progressive joint pain, skin hyperelasticity, and easy bruising. She has a history of recurrent joint dislocations since childhood. Skin biopsy shows abnormal collagen fibrils with irregular diameter and spacing. Genetic testing reveals a mutation in the COL5A1 gene encoding type V collagen. Which structural level of collagen is most directly affected by this mutation?

Which of the following amino acids contains a thiol (-SH) group in its side chain and is capable of forming disulfide bonds with another identical residue?

In a protein with quaternary structure, what is the term used to describe the individual polypeptide chains that associate together to form the native protein complex?