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A dvanced process modelling with m ultivariate curve resolution. Anna de Juan 1,(*) and Romà Tauler 2 . Chemometrics group. Universitat de Barcelona. Diagonal, 647. 08028 Barcelona. [email protected] Dept. of Environmental Chemistry. IIQAB-CSIC. Barcelona. - PowerPoint PPT Presentation
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Advanced process modelling with multivariate curve resolution
Anna de Juan1,(*) and Romà Tauler2.
1. Chemometrics group. Universitat de Barcelona. Diagonal, 647. 08028 Barcelona. [email protected]
2. Dept. of Environmental Chemistry. IIQAB-CSIC. Barcelona.
Process. Definition and underlying model.
Evolving chemical system monitored by a multivariate signal.
Reaction system with a known mechanism (kinetic process)
Evolving system with inexistent mechanism (chromatographic elution)
Tim
e
Spectrum
Kin
etic
tra
ce
Tim
e
Spectrum
Kin
etic
tra
ce
Elu
tio
nti
me
Spectrum
Chr
omat
ogra
m
Elu
tio
nti
me
Spectrum
Chr
omat
ogra
m
D DA DB
= +
DADB
D
= +
s A
cB
s B
cA
A cB
sA
c
sB
Process. Definition and underlying model.
D
=
C
ST
sB
sA
cBcA
C ST
D = CST + E Bilinear model
Known mechanism
Hard-modeling (HM)No mechanism
Soft-modeling (SM)
Process. Definition and underlying model.
=
D
Tim
e
A B C
CST
A B C
Wavelength
Ab
so
rba
nc
e
Time
Co
nc
en
tra
tio
n
Wavelength
Ab
so
rpti
vit
ies
Wavelength
Ab
so
rba
nc
e
Wavelength
Ab
so
rba
nc
e
Time
Co
nc
en
tra
tio
n
Time
Co
nc
en
tra
tio
n
Wavelength
Ab
so
rpti
vit
ies
Wavelength
Ab
so
rpti
vit
ies
WavelengthsRetention times WavelengthsWavelengthsRetention timesRetention times
Ordered evolving concentration pattern
Process soft-modeling(Multivariate Curve Resolution, MCR)
MCR in process analysis
D
Tim
e
0 10 20 30 40 50 60 70 80 90 1000
0.5
1
1.5
2
2.5
Wavelength
Ab
so
rba
nc
e
Process raw data
=
A B C
C
ST
A B C
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time
Co
nc
en
tra
tio
n0 10 20 30 40 50 60 70 80 90 100
0
0.5
1
1.5
2
2.5
3x 10
4
Wavelength
Ab
so
rtiv
itie
s
D = CST
Process description
MCR
Evolution of process
contributions(model)
Structural information of compounds
(identification)
Multivariate Curve Resolution – Alternating Least Squares (MCR-ALS)
Determination of the number of components (PCA).
Building of initial estimates (C or ST) (EFA, SIMPLISMA, prior knowledge...)
Iterative least squares calculation of C and ST subject to constraints.
Check for satisfactory CST data reproduction.
Data exploration
Input of external information
Optimal and chemically meaningful process description
D = CST + E
R. Tauler. Chemom. Intell. Lab. Sys. 30 (1995) 133. A. de Juan and R. Tauler. Anal. Chim. Acta 500 (2003) 195.J. Jaumot et al. Chemom. Intell. Lab. Sys. 76 (2005) 101.
Constraints
DefinitionAny property systematically present in the profiles of the compounds in our data set.
Chemical origin Mathematical properties.
ApplicationC and S can be constrained differently.
The profiles within C and ST can be constrained differently.
Reflect the inherent order in a process
Process constraints
Unconstrained profiles
0 5 10 15 20 25 30 35-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
Constrained profiles (C*)5 10 15 20 25 30 35
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
Unconstrained profiles
0 5 10 15 20 25 30 35-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
Unconstrained profiles
0 5 10 15 20 25 30 35-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0 5 10 15 20 25 30 35-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
Constrained profiles (C*)5 10 15 20 25 30 35
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
Constrained profiles (C*)5 10 15 20 25 30 35
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
Constrained profiles (C*)5 10 15 20 25 30 35
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
Constrained profiles (C*)5 10 15 20 25 30 35
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
5 10 15 20 25 30 35-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
Non-negativity (C, S)
Unconstrained profiles
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
Constrained profiles (C*)
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
Unconstrained profiles
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
Unconstrained profiles
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
Constrained profiles (C*)
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
Constrained profiles (C*)
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
Constrained profiles (C*)
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
Unimodality (C)
Processes evolving in
emergence-decay profilesctotal
Unconstrained profiles5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
0.3
Mass balance
= ctotal
ctotal
Constrained profiles (C*)0 5 10 15 20 25 30 35
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
ctotal
Unconstrained profiles5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
0.3 ctotal
Unconstrained profiles5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
0.3
Unconstrained profiles5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
0.3
5 10 15 20 25 30 35
0.05
0.1
0.15
0.2
0.25
0.3
Mass balanceMass balance
= ctotal
ctotal
Constrained profiles (C*)0 5 10 15 20 25 30 35
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
= ctotal
ctotal
Constrained profiles (C*)0 5 10 15 20 25 30 35
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 5 10 15 20 25 30 350
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Closure (C)
Mass balance
Selectivity!!
MCR in process modellingAdvantages (low requirements)
Bilinear data structure
No process model required.
No previous identification of process compounds needed.
Limitations We model what we measure (non-absorbing species)
Each compound should have a distinct concentration profile and spectrum (rank-deficiency).
MCR in process modelling
Limitations We model what we measure (non-absorbing species)
Each compound should have a distinct concentration profile and spectrum (rank-deficiency).
Multiset process analysis
Incorporation of hard-modelling information
Advanced process modelingMultiset analysis
Processes and multiset modelsThe same process monitored with different techniques
Several processes/batches monitored with the same technique
Several processes monitored with several
techniques
Multiset arrangements. Advantages.
The chemometric reasons Rotational ambiguity decreases/is suppressed. Rank-deficiency problems are solved. Noise effect is minimized
The chemical reasons More information introduced in the process modelling. More robustness in the process description. Better characterization of process compounds
(multitechnique analysis). More global description of process evolution and of effect of
inducing agents. (multiexperiment analysis).
Rank-deficient systems(the concept)
Detectable rank < nr. of process contributions
=
D C
ST
Rank(D) = min(rank C, rank ST)
Equally shaped concentration profiles
A + B C
[A] = [B]
Rank 2
Equally shaped spectra
D L (enantiomers)
Spectra D = Spectra L
Rank 1
Rank-deficiency can be linked to C or to ST
Rank-deficient systems(the concept)
Equally shaped concentration profiles
A + B C
Rank 2
=
D C
ST
cBcA
[A]o = 1 [B]o = 3
3cA = cB (rank 2)
D1
=
D C
ST
[A]o = 2 [B]o = 1
cBcA
cA = 2cB (rank 2)
D2
Rank-deficient systems(the concept)
[A]o = 1 [B]o = 3[A]o = 2 [B]o = 1
3cA = cB
=ST
cBcAD1
DC
cBcA
cA = 2cB
D2
=ST
D1
DC
cBcA
cA kcB (rank 3)
D2
Breaking rank-deficiency(multiset data)
=
C
SUVT
sA = ksB
sB
sA
SCDT
sA ksB
sB
sA
DUV
D
DCD
=
C
ST
sB
sA
DUV
D
DCD
sA ksB
(rank 2)
Multitechnique process analysis
Multitechnique data analysis
Only the concentration direction is shared by all experiments. Completely different techniques can be treated together
Higher spectral discrimination power among compounds.
The augmented response contains complementary information of all techniques (‘superspectrum’).
The single matrix of process profiles provides cleaner process profiles and a more robust description of the process.
Process profiles are not affected by specific noise patterns of particular techniques.
Process description should be valid for all measurements collected.
Multiset multi-way
ON
FeON
Fe
pH-induced transitions in hemoglobin
Spectroscopic monitoring between pH 1.5 and 10.5 Changes in secondary structure
UV (350-650 nm), far-UV CD (200-250 nm) Changes in tertiary structure
UV, near-UV CD (250-350 nm), fluorescence (300-450 nm)
Binding of heme group
UV, Soret CD (380-430 nm)
Evolution of protein conformations Global process: many events at different structural levels. No mechanism defined.
Muñoz, G.; de Juan, A. Anal. Chim. Acta 2007, 595, 198.
pH-induced transitions in hemoglobin(single technique resolution)
D1pH D2
pH D3pH D4
pH D5pH
UVFar-UV CD
200 210 220 230 240 250
-15
-10
-5
0
5
10
15
20
D1
300 350 400 4500
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
D4
350 450 550 6500
0.2
0.4
0.6
0.8
1
D5
Fluorescence
250 275 300 325 350-4
-2
0
2
4
6
8
10
D3
Near-UV CD
Wavelengths (nm)
Soret CD
380 390 400 410 420 430-10
-5
0
5
10
15
20
D2
Wavelengths (nm)Wavelengths (nm) Wavelengths (nm) Wavelengths (nm)
pH1.5 10.5
2ary structure 3ary structureHeme binding Global
pH-induced transitions in hemoglobin(single technique resolution)
Technique Chemical eventNr. of
process contributions
pH transition values
Explained variance (%)
Far-UV CD Changes 2ary structure 2 4.0 99.75
Near-UV CD Changes 3ary structure 2 4.5 93.83
Fluorescence Changes 3ary structure 3 4.2 / 8.7 99.96
Soret CD Heme binding 2 7.8 99.77
UV-visible Global process 4 2.8 / 3.9 / 8.5 99.75
Some chemical events are simpler than the global process.
Non absorbing species are not modelled.
Too similar spectral contributions may not be distinguished.
Multitechnique analysis is needed to complete the puzzle.
pH-induced transitions in hemoglobinGlobal process resolution (multitechnique analysis)
D1 D2 D3 D4 D5pH
UVFar-UV CD
200 210 220 230 240 250
-15
-10
-5
0
5
10
15
20
D1
300 350 400 4500
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
D4
350 450 550 6500
0.2
0.4
0.6
0.8
1
D5
FluorescenceNear-UV CD
250 275 300 325 350-4
-2
0
2
4
6
8
10
D3
Wavelengths (nm)
Soret CD
380 390 400 410 420 430-10
-5
0
5
10
15
20
D2
Wavelengths (nm)Wavelengths (nm) Wavelengths (nm) Wavelengths (nm)
pH-induced transitions in hemoglobinGlobal process resolution
300 350 400 4500
5
10
15
20
Fluorescence
Wavelengths (nm)195 205 215 225 235 245
-20
-10
0
10
20
Far-UV CD
Wavelengths (nm)
350 400 450 500 550 600 6500
5
10
15
20
UV
Wavelengths (nm)250 270 290 310 330 350-5
0
5
10
Near-UV CD
Wavelengths (nm)380 390 400 410 420 430
-10
0
10
20
Soret CD
Wavelengths (nm)
pH0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10
Non-absorbing species are modelled (Soret CD).
Similar spectral contributions are distinguished (near-UV CD).
C
S1T (2)* S3
T (2)S2T (2) S4
T (3) S5T (4)
* Figures in parentheses are number of resolved species in single technique analysis.
Native HbD1OxyHbD2
Multiexperiment process analysis
Multiexperiment data analysisOnly the spectral direction is shared by all experiments. No batch synchronisation is needed. Process induced by different agents and performed in
different conditions can be treated together
The single matrix ST provides cleaner pure spectra and a more robust structural characterisation of process compounds.
Easier modelling of minor process contributions by using experiments with complementary information.
Good experimental design may provide experiments with presence/absence of different species.
Multiset multi-way
Protein-drug interaction
Dominant at low [ligand:protein] ratio
and low [ligand].
Meso-tetrakis(p-sulf onatephenyl )porphyrin (TSPP)
Loop E-FGlu89
cavity
-lactoglobulin Meso-tetrakis(p-sulf onatephenyl )porphyrin (TSPP)
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
-lactoglobulin Meso-tetrakis(p-sulf onatephenyl )porphyrin (TSPP)
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
-lactoglobulin Meso-tetrakis(p-sulf onatephenyl )porphyrin (TSPP)
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
Loop E-FGlu89
cavity
-lactoglobulin
Protein + TSPP [Protein-TSPP]complex TSPPaggregate
Dominant at high [ligand:protein] ratio and
high [ligand].
Multiexperiment analysis of experiments enhancing low and high [protein:ligand] ratios help in the definition of all species involved.
Protein-drug interaction
D1: protein-ligand complex dominates.D2: aggregate dominates
=
[ligand]
2 M
[protein]
5 M
[p
rote
in]
[lig
and
]
C
ST.
C1
C2
D
[pro
tein
][l
igan
d]
=
[ligand]
2 M
[protein]
5 M
[p
rote
in]
[lig
and
]
C
ST.
C1
C2
D
[pro
tein
][l
igan
d]
400 500 600 7000
0.1
0.2
0.3
0.4
0.5
Abso
ban
ce (
a.u
.)
0 M
7.5 M
Pro
tein
con
cen
trati
on
D1
400 500 600 7000
0.5
1
1.5
2
2.5
3
3.5
4
Wavelength (nm)
Ab
sorb
ance
(a.u
.)
0 M
40 M
TS
PP
con
cen
trati
on
D2
Protein-drug interaction
350 400 450 500 550 600 650 700 7500
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Wavelength (nm)
Ab
sorb
ance
(a.u
.)
ST
0 5 10 15 20 25 30 35 400
5
10
15
20
25
TSPP concentration ( M)
Con
cent
rati
on (
a.u.
)
TSPPProtein-TSPP
TSPPaggregate
C2
TSPPProtein-TSPP
C1
0 1 2 3 4 5 6 70
2
4
6
8
10
12
Protein concentration (M)
Con
cent
rati
on (
a.u.
)
0 5 10 15 20 25 30 35 400
5
10
15
20
25
TSPP concentration ( M)TSPP concentration ( M)
Con
cent
rati
on (
a.u.
)
TSPPProtein-TSPP
TSPPaggregate
C2
TSPPProtein-TSPP
C1
0 1 2 3 4 5 6 70
2
4
6
8
10
12
Protein concentration (M)
Con
cent
rati
on (
a.u.
)
TSPPProtein-TSPP
C1
0 1 2 3 4 5 6 70
2
4
6
8
10
12
Protein concentration (M)Protein concentration (M)
Con
cent
rati
on (
a.u.
)
The aggregate could not be recovered using only D1
TSPP and the complex are very minor to be correctly recovered only from D2
The different presence/absence of species in D1 and D2 and the decorrelated information in terms of [TSPP:complex:aggregate] helps to a better definition of the pure spectra.
Advanced process modeling(Incorporating hard models)
Process modelling
Hard-modeling. The variation of a process is fully described by fitting a specific mathematical model (physicochemical or empirical) to the experimental measurements.
Soft-modeling. The variation of a process is described by the bilinear model of the measurements, optimised under chemical and/or mathematical constraints. No explicit mathematical model is used.
Process hard-modeling
0 10 20 30 40 50 60 70 80 90 1000
0.5
1
1.5
2
2.5
3x 104
Wavelengths
Ab
so
rtiv
itie
s
LS (D, C)(ST)
ST
Output: C, S and model parameters.
Unique solutions
The model must describe all the experimental variation.
0 10 20 30 40 50 60 70 80 90 1000
0.5
1
1.5
2
2.5
Wavelength
Ab
so
rba
nc
e
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time
Co
nc
en
tra
tio
n
D C
Non-linear model Fitting
min(D(I-CC+)C = f(k1, k2)
D = CST ; D = CC+D
Process Hard modeling (multibatch/multiexperiment)
Need of one global model
or
Knowledge of the link expression among different batch models
Batch/exp. 1
D C
ST
=
Batch/exp. 2
Batch/exp. 3
Batch/exp. n
Link among batches model
Soft- modeling (one experiment)
0 10 20 30 40 50 60 70 80 90 1000
0.5
1
1.5
2
2.5
3x 104
Wavelengths
Ab
so
rtiv
itie
s
ST
0 10 20 30 40 50 60 70 80 90 1000
0.5
1
1.5
2
2.5
Wavelength
Ab
so
rba
nc
e
D C
Constrained ALS optimisationLS (D,C) S*LS (D,S*) C*min (D –C*S*)
,
Output: C and S.
Solutions might be ambiguous.
All absorbing contributions in and out of the process are modelled.
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time
Co
nc
en
tra
tio
n
Soft-modeling (multibatch/multiexperiment)
Batch/exp. 1
D C
ST
=
Batch/exp. 2
Batch/exp. 3
Batch/exp. n
Different experiments can be analysed together
Experimental conditions, link among batches may be unknown.
Link among batches pure spectra
Incorporating hard-modeling in MCR
All or some of the concentration profiles can be constrained.
All or some of the batches can be constrained.
A B C X
C C
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time
Con
cent
ratio
n (a
.u.)
A
B
C
X
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time
Con
cent
ratio
n (a
.u.)
A B C XA
B
C
X
CSM CHM
Non-linear model fitting
min(CHM - CSM)CHM = f(k1, k2)
Hybrid hard- and soft-modeling MCR (HS-MCR)
Output: C, S and model parameters.
Hard models and soft-modeling constraints act simultaneously.
Off-process contributions can be modelled separately.
Process model can be recovered in the presence of absorbing interferences.
0 10 20 30 40 50 60 70 80 90 1000
0.5
1
1.5
2
2.5
3x 104
Wavelengths
Ab
so
rtiv
itie
s
ST
0 10 20 30 40 50 60 70 80 90 1000
0.5
1
1.5
2
2.5
Wavelength
Ab
so
rba
nc
e
D C
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time
Co
nc
en
tra
tio
n
HS-MCR (multibatch/multiexperiment)
Batch/exp. 1
D C
ST
=
Batch/exp. 2
Batch/exp. 3
Batch/exp. n
Link among batches (pure spectra)
Global or individual models can be used.Link among different models can be unknown or inexistent.Model-free and model-based experiments can be analysed together.
Myoglobin denaturation
Mechanism
Steady-state process
Native (N) Intermediate (Is) Denatured (D)
Kinetic transient (It)
Kinetic process
Steady-state processUV spectra, pH range 7.0-2.0
N Is ? D
Unknown model
Kinetic processUV spectra, pH-jump stopped-flow
First-order consecutive reactions
D?IN 21 kt
k
P. Culberg, P.J. Gemperline, A. de Juan. (submitted)
Hard-modelling (kinetic unfolding, 1st order reactions)
Soft-modelling constraints
Myoglobin denaturation
=
Steady-state
unfolding
Kinetic unfolding
p
Hti
me
C
ST
.CpH
Ct
Dp
Hti
me
Model-free and model-based experiments can be analyzed together.
Myoglobin denaturation
Formation of a kinetic transient was detected and hard-modelled.k1 = 4.05 s.1 k2 = 0.62 s-1
Steady-state unfolding was modelled with soft constraints.
Steady-state process
Native (N) Denatured (D)
Kinetic transient (It)
Kinetic process
10
pH time
Wavelengths
BDE-209 (flame retardant)
Photodegradation of decabromodiphenil ether
OBr
Br
Br
Br
Br
Br
BrBr
BrBr
UV kinetic monitoring in several THF/ water mixtures(10% water, 20% water, 30% water, 40% water)
Three replicates per solvent composition.
Wavelength (nm)
S. Mas, A. de Juan, S. Lacorte, R. Tauler (submitted)
Data arrangement
Global model 1
Global model 2
One global kinetic model per solvent composition
k3 C
k2 B
k1 A D
Off-process contribution(spectral solvent effects)
Photodegradation of BDE-20940% water
C
10% water 20% water 30% water
1 2 3 1 2 3 1 2 1 2 3
ST
Composition k1 (x 10-4)* k2 (x 10-4)* k3 (x 10-4)*
90:10 THF-water 2.76 (1) 2.60 (2) 1.38 (6)
80:20 THF-water 2.448 (8) 1.613 (5) 1.362 (4)
70:30 THF-water 2.41 (1) 0.99 (4) 0.77 (4)
60:40 THF-water 1.933 (6) 1.092 (3) 0.68 (2)
k3 C
k2 B
k1 A D Off-process contribution
Rate constants
MCR in process modelling. Conclusions
Low requirements
Bilinear data structure
No process model required.
No previous identification of process compounds needed.
High flexibility
In data arrangements Multitechnique analysis Multiexperiment analysis. Multitechnique and
multiexperiment analysis.
In input information Soft-modeling constraints. Hard models. Adaptable to individual
compounds and/or experiments.
Acknowledgements
Glòria Muñoz (pH-dependent hemoglobin example)
Susana Navea (Protein-drug interaction).
Sílvia Mas (UB and IIQAB-CSIC) (BDE-209 example)
Pat Culberg, East Carolina University (myoglobin example).
Lionel Blanchet, UB and Université des Sciences et Technologies de Lille (photochemical example)
Financial support by Spanish Government
Group Web page: www.ub.es/gesq/mcr/mcr.htm
Process. Definition and underlying model.
Evolving chemical system monitored by a multivariate signal.
Reaction system with a known mechanism (kinetic process)
Evolving system with inexistent mechanism (chromatographic elution)
Pro
cess
var
iab
leMeasurement channel
Protein photochemical reaction
Photochemical kinetic process
Protein conformational change
)()( 21 QubiquinolQUbiquinone h
)(.)(. 21 PconformfinalPconformInitial h
Light on Light off
time21
1 QQ k 211 QQ k
21 PP 21 PP
Measurement: IR rapid-scan spectroscopy(difference spectra) (1200-1800 cm-1)
Fe
P
BA
HA
QA
QB
HB
BB
Qi
2QH2
QH2
Q
Q40 ÅCytochrome
complex
Reaction
center
CYTOPLASM2 H + 2 H +
4 H +
h
e-
Q1
Q2
Photosynthetic reaction center Rhodobacter Spheroides
Blanchet, L.; Ruckebusch, C.; Huvenne, J. P.; de Juan, A. Chemom. Intell. Lab. Sys. 2007, 89, 26.
Protein photochemical reactiontim
e
Light on
Light off
Kinetics of ubiquinol are modelled in the presence of an interference (protein absorption).
time
Q2 P2
C
ST
Hard-modeling (ubiquinol formation and decay contribution)Soft-modeling constraints
=
D
Protein photochemical reaction
Kinetics of ubiquinol formation and decay are modelled (hard-modeling constraint).
k1 = 7 10-4 s-1
k-1 = 10-4 s-1
Photoinduced protein conformational change (model-free) is modelled.
-2
-1
0
1
2
OffOn
Time (s)
Wavenumber (cm-1)
12001800
60
Amide IIAmide I
-Q1
+Q2
Rotational ambiguity and noise minimization
Single setof process profilesfor all techniques
C,ST possible combinations with optimal fit are less(rotational ambiguity
decreases)
Noise is technique- and data set-dependent.
C encloses common information for all techniques (noise effect is minimized)
Breaking rank-deficiency(multiset data)
=
D C
SCDT
sA ksB
(rank 2)sB
sA
DCD
=
D C
SUVT
sA = ksB
(rank 1)sB
sA
DUV
Equally shaped spectra
D L (enantiomers)
Spectra D = Spectra L
Rank 1
D = CST
D = CT inv(T)ST