Table 1.
Physical properties of homo- and hetero-oligomers of recombinant β-crystallins
| β-crystallin | Calculated Mr1 | SEC | AUC | association model (reference) | ||
|---|---|---|---|---|---|---|
| monomer | dimer | Mr2 | Mr3 | Kd | ||
| self-association | ||||||
| mouse B1 | 28.0 | 56.0 | 35 | 47.3 | 1.5 × 10−6 M | monomer-dimer (34) |
| mouse B1ΔN56 | 22.9 | 45.8 | 71 | 74.6 | 5.4 × 10−17M3 | monomer-tetramer |
| mouse B1ΔN47 | 23.6 | 47.2 | - | 39.4 | 1.4 × 10−6 M | monomer-dimer |
| human A3 | 25.1 | 50.2 | 42 | 42.6 | 4.5 × 10−6 M | monomer-dimer |
| human A3ΔN30 | 21.9 | 43.8 | 20* | 44.3 | 0.1 × 10−6 M | dimer |
| mouse A3 | 25.2 | 50.4 | 40 | 42.6 | 5.1 × 10−6 M | monomer-dimer (26) |
| mouse A3ΔN30 | 21.8 | 43.6 | 23* | 42.7 | 0.7 × 10−6 M | monomer-dimer (26) |
| mouse B2 | 23.4 | 46.8 | 37 | 37.6 | 4.6 × 10−6 M | monomer-dimer (26) |
| mouse B2ΔN17 | 21.7 | 43.4 | 36 | 34.5 | 9.7 × 10−6 M | monomer-dimer (26) |
| hetero-association | ||||||
| B1:A3 | 28.0:25.1 | 53.1 | 71 | 96.0 | 1.1 × 10−6 M | dimer-tetramera (34) |
| B1:A3ΔN30 | 28.0:21.8 | 49.8 | 70 | 85.8 | 5.0 × 10−6 M | dimer-tetramer |
| B1ΔN56:A3 | 22.9:25.1 | 48.1 | 47 | - | - | no association |
| B1ΔN47:A3 | 23.6:25.1 | 48.7 | - | 89.0 | 0.2 × 10−6 M | dimer-tetramer |
| B1ΔN56:A3ΔN30 | 22.9:21.8 | 44.8 | - | - | - | no association |
| B2:A3 | 23.4:25.2 | 48.6 | 49 | 50.0 | - | hetero-dimerb (6) |
| B2:A3 | 23.4:25.2 | 48.6 | - | 90.0 | - | hetero-tetramerc (6) |
Polypeptide molecular weights in kDa were calculated from the protein sequences (consistent with NCBI sequence of βB1-NP_076184, βA3 - NP_005199, and βB2 - NP_031799). Murine βA3 and βB2 show 95%, and 97% identity with their human species, respectively with ~50% sequence identity shared among the pairs of β-crystallins independently on species; the globular domains of human and mice βB1-crystallin are about 80% identical and ~92% similar by their amino acid properties which provide a reasonable basis for comparison a role of their globular domains and terminal extensions on β-crystallin association (34)
Apparent molecular weights in kDa analyzed by size exclusion chromatography
Weight-average molecular weights in kDa determined by AUC; Kd (M) dissociation constants from analytical ultracentrifugation. Samples were analyzed in the concentration range of 0.5-2 mg/mla, <1 mg/mlb, >1 mg/mlc; 4The wild-type and truncated βB1 and βA3 were expressed in E.coli (34) and βB2 was expressed in baculovirus system (26) or isolated from bovine lenses (6)
Proteins which elutes on SEC as apparent monomers due to the interaction with the column matrix).