Intra- and interchain disulfide bond generation in S100b protein

Area of Science:

• Biochemistry
• Protein Chemistry
• Cell Signaling

Background:

• S100b protein is implicated in neurite extension.
• Disulfide-bridged proteins are typically formed from reduced counterparts under physiological redox conditions.
• The formation and function of disulfide-bridged S100b remain unclear.

Purpose of the Study:

• To investigate the formation of disulfide-bridged S100b protein under various ionic and redox conditions.
• To determine if disulfide-bridged S100b can be generated from reduced S100b under native conditions.
• To assess the structural and functional properties of oxidized S100b species.

Main Methods:

• Studying S100b protein under nondenaturing and denaturing conditions.
• Utilizing various ionic conditions (no ions, Ca2+, Zn2+, K+).
• Employing different redox conditions to induce disulfide bond formation.
• Characterizing oxidized S100b species.

Main Results:

• Disulfide-bridged S100b species were not generated from reduced proteins under native conditions, irrespective of ionic or redox state.
• Mixed disulfides were observed in some cases.
• Intrasubunit and intersubunit disulfide-bridged species formed readily under denaturing conditions.
• Oxidized species under denaturing conditions exhibited structural differences and likely impaired Ca2+ binding compared to reduced S100b.

Conclusions:

• The formation of disulfide-bridged S100b protein under physiological conditions is questionable.
• Disulfide-bridged S100b species generated under denaturing conditions may not be biologically relevant due to structural and functional alterations.
• Further research is needed to clarify the in vivo role of S100b oxidation states.