SUPPLEMENTARY INFORMATION FOR:
TFA as excipient destabilizes melittin causing the selective
aggregation of melittin within the centrin-melittin-TFA complex1)
Belinda Pastrana-Rios,1,2,2) Liliana del Valle Sosa,1 and Jorge Santiago,1
1Department
2Protein
of Chemistry, University of Puerto Rico, Mayagüez Campus, Call Box 9019, Mayagüez, PR 00681, USA
Research Center University of Puerto Rico, Mayagüez, PR 00681-9019, USA
Supplementary Material:
Table 1S. Order of events during temperature perturbation for: MLT-TFA and 13C-Cr cen.
Table 2S. Sequential order of events summarizing the temperature perturbation for:
13
C-Cr cen-MLT-TFA (1:2:20 molar ratio) complex.
FIG 4S. FT-IR spectral overlay of the 13C-Cr cen-MLT-TFA complex (1:1:10 molar ratio)
within the spectral region of 1720-1540 cm-1 along with the 2D IR correlation analysis.
1)
Contributed paper, published as part of a Special Topic: Invited Papers of the 2 nd International BioXFEL
Conference, Ponce, Puerto Rico, January 14-16, 2015.
2)
To whom correspondence should be addressed. Electronic mail: belinda.pastrana@upr.edu
1
Table 1. Order of events during temperature perturbation for: MLT-TFA and 13C-Cr cen.
Event
Order of Events*
13C-Cr
cen
1
-helix (1597.3 cm-1) → Arg N-D s (1584.7 cm-1), Arg 13C-N (1572 cm-1)
2
Arg 13C-N (1572 cm-1) → Arg N-D s (1584.7 cm-1)
3
Arg N-D s (1584.7 cm-1) → Arg N-D as (1611 cm-1)
4
Arg N-D as (1611 cm-1) → -helix (1624 cm-1))
5
-helix (1624 cm-1) → hinge loops (1636 cm-1), CaBS loops (1640 cm-1
6
CaBS loops (1640 cm-1) → hinge loops (1636 cm-1),
MLT-TFA complex
1a
random coil (1656.1 cm-1) → 310-helix (1643 cm-1), -sheet (1631.3 cm-1)
2
random coil (1656.1 cm-1), -sheet (1631.3 cm-1) → TFA (1673.1 cm-1)
3
310-helix (1643 cm-1) → -sheet (1631.3 cm-1)
4
Arg (1606 & 1582.4 cm-1) → kink (1664.4 cm-1)
5a
kink (1664.4 cm-1) → -turn (1685 cm-1)
*Peak assignment and cross peak positions have been used to describe each event.
a
The kink is due to the presence of the proline in the MLT sequence, and the -turn (1685 cm-1)
along with the presence of the -sheet (1631.3 cm-1) allows for the assignment of antiparallel
pleated sheet.
2
Table 2. Sequential order of events summarizing the temperature perturbation for:
13
C-Cr cen-MLT-TFA complex (1:2:20 molar ratio).
Event
Order of Events*
13C-Cr
1
2a
cen-MLT-TFA complex
13
C-Cr cen’s Arg *C-N (1573 cm-1) → aggregation (1619 cm-1)
MLT’s -strand (1628-1cm-1),13-sheet (1638 cm-1) → MLT’s -turn
(1674.7 cm-1)
-1
aggregation (1619 cm ) → C-Cr cen’s *-helices (1597 cm )
3
13
C-Cr cen’s Arg N-D (1581 cm-1) → MLT’s rc (1655 cm-1)
4
MLT’s rc (1655 cm-1) → TFA (1673.1 cm-1)
5
MLT’s 310-helix (1645 cm-1) → MLT’s kink (1664.4 cm-1)
6
MLT’s kink (1664.4 cm-1) → MLT’s -turn (1685 cm-1)
*Peak assignment and cross peak positions have been used to describe each event.
a13
C-Cr cen’s shifts to even lower wavenumbers due to its interaction with TFA through its
arginine residues.
3
Fig. 4S. Overlaid FT-IR spectra comprised of the amide I’/I’* bands for: (A) 13C-Cr cen-MLTTFA complex (1:1:10 molar ratio) in the spectral region of 1720-1540 cm-1. (B) Synchronous
and (C) Asynchronous plots.
4