A 52-year-old man comes to the office for follow-up of hyperlipidemia. He was diagnosed 5 years ago and has been inconsistently adherent to statin therapy. His father died of myocardial infarction at age 48. He has smoked one pack of cigarettes daily for 30 years but quit 6 months ago. He does not exercise regularly. His blood pressure is 138/86 mm Hg. Physical examination shows central obesity with a waist circumference of 106 cm (42 in). Laboratory studies show total cholesterol of 285 mg/dL, LDL cholesterol of 195 mg/dL, HDL cholesterol of 38 mg/dL, and hemoglobin A1c of 5.8%. The physician counsels him on the importance of statin adherence to reduce cardiovascular risk and discusses lifestyle modifications. A medical student asks the physician to explain how LDL particles that enter the arterial wall are taken up by macrophages through scavenger receptors rather than the usual LDL receptors.
Which of the following chemical processes must occur to LDL particles trapped in the arterial wall to enable scavenger receptor recognition?