Motixafortide: Molecular Structure

Molecular Structure#

Motixafortide is a synthetic heterodetic cyclic peptide designed as a high-affinity CXCR4 antagonist. It is derived from the T140 peptide scaffold originally developed for CXCR4-targeted anti-HIV research.

Chemical Properties#

Structural Design#

Key Design Features#

Motixafortide incorporates several structural modifications that optimize CXCR4 binding:

1. 4-Fluorobenzoyl N-terminus: A fluorinated aromatic cap that enhances metabolic stability and contributes to CXCR4 binding
2. Non-natural amino acids: Includes naphthylalanine (Nal) and citrulline (Cit) residues that provide enhanced binding affinity and selectivity
3. Disulfide bridge: Creates the cyclic structure that constrains the peptide conformation for optimal receptor binding
4. Six cationic residues: Establish critical charge-charge interactions with acidic residues in the CXCR4 binding pocket
5. Two bulky synthetic moieties: Restrict conformational flexibility of key residues involved in CXCR4 activation

CXCR4 Binding#

Structural studies (PMID 36901829) have elucidated the binding mode of motixafortide in the CXCR4 chemokine receptor, revealing extensive interactions within the receptor binding pocket that explain its exceptionally high affinity (Ki 0.32 nM).

Pharmacokinetic Properties#

Comparison with Plerixafor#

Stability#

The cyclic structure, non-natural amino acids, and fluorobenzoyl modification contribute to the metabolic stability of motixafortide. The extended duration of clinical activity (>48 hours) reflects both high receptor affinity and resistance to proteolytic degradation.

Molecular Context#

Motixafortide belongs to the Immune category of research peptides. The molecular properties of Motixafortide determine its pharmacological behavior, including receptor binding, distribution, metabolism, and elimination. Understanding these properties is fundamental to interpreting clinical data and designing research protocols.

Structural Overview#

Motixafortide is characterized as: Motixafortide is a synthetic 14-amino acid cyclic peptide with a molecular weight of 2159.55 Da and the molecular formula C97H144FN33O19S2. It is a heterodetic cyclic peptide derived from the T140 scaffold with a 4-fluorobenzoyl group at the N-terminus. The peptide contains six cationic residues that establish charge-charge interactions with acidic CXCR4 residues, and two synthetic bulky chemical moieties that restrict conformations of important residues associated with CXCR4 activation..

Amino Acid Sequence Details#

The amino acid sequence of Motixafortide is: 14-amino acid heterodetic cyclic peptide containing non-natural amino acids including naphthylalanine (Nal) and citrulline (Cit), with a disulfide bridge and N-terminal 4-fluorobenzoyl modification. This sequence determines the peptide's three-dimensional structure, receptor binding properties, and biological activity.

Pharmacokinetic Profile#

Half-Life: Extended clinical activity exceeding 48 hours

The half-life of a peptide influences dosing frequency, duration of effect, and the clinical utility of the compound. Researchers should consider the half-life when designing experimental protocols.

Related Reading#

• Motixafortide overview and research guide
• Peptides similar to Motixafortide
• Motixafortide research evidence