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55 \author{Don Armstrong}
56 \title{OOL Kinetic Formalisms}
62 <<results=hide,echo=FALSE>>=
66 to.kcal <- function(k,temp=300) {
68 return(-gasconst*temp*log(k)/1000)
72 \section{State Equation}
73 % double check this with the bits in the paper
75 Given a base forward kinetic parameter for the $i$th specie $k_{fi}$
76 (which is dependent on lipid type, that is PC, PE, PS, etc.), an
77 adjustment parameter $k_{fi\mathrm{adj}}$ based on the vesicle and the
78 specific specie (length, unsaturation, etc.) (see~\fref{eq:kf_adj}),
79 the molar concentration of monomer of the $i$th specie
80 $\left[C_{i_\mathrm{monomer}}\right]$, the surface area of the vesicle
81 $S_\mathrm{ves}$, the base backwards kinetic parameter for the $i$th
82 specie $k_{bi}$ which is also dependent on lipid type, its adjustment
83 parameter $k_{bi\mathrm{adj}}$ (see~\fref{eq:kb_adj}), and the molar
84 concentration of the $i$th specie in the vesicle $C_{i_\mathrm{ves}}$,
85 the change in concentration of the $i$th specie in the vesicle per
86 change in time $\frac{d C_{i_\mathrm{ves}}}{dt}$ can be calculated:
89 \frac{d C_{i_\mathrm{ves}}}{dt} = k_{fi}k_{fi\mathrm{adj}}\left[C_{i_\mathrm{monomer}}\right]S_\mathrm{ves} -
90 k_{bi}k_{bi\mathrm{adj}}C_{i_\mathrm{ves}}
94 For $k_{fi}k_{fi\mathrm{adj}}\left[C_{i_\mathrm{monomer}}\right]$,
95 $k_{fi}$ has units of $\frac{\mathrm{m}}{\mathrm{s}}$,
96 $k_{fi\mathrm{adj}}$ and $k_{bi\mathrm{adj}}$ are unitless,
97 concentration is in units of $\frac{\mathrm{n}}{\mathrm{L}}$, surface
98 area is in units of $\mathrm{m}^2$, $k_{bi}$ has units of
99 $\frac{1}{\mathrm{s}}$ and $C_{i_\mathrm{ves}}$ has units of
100 $\mathrm{n}$, Thus, we have
103 \frac{\mathrm{n}}{\mathrm{s}} = \frac{\mathrm{m}}{\mathrm{s}} \frac{\mathrm{n}}{\mathrm{L}} \mathrm{m}^2 \frac{1000\mathrm{L}}{\mathrm{m}^3} -
104 \frac{1}{\mathrm{s}} \mathrm{n}
106 \frac{\mathrm{m^3}}{\mathrm{s}} \frac{\mathrm{n}}{\mathrm{L}} \frac{1000\mathrm{L}}{\mathrm{m}^3} - \frac{\mathrm{n}}{\mathrm{s}}=
107 \frac{\mathrm{n}}{\mathrm{s}} = 1000 \frac{\mathrm{n}}{\mathrm{s}} - \frac{\mathrm{n}}{\mathrm{s}}
108 \label{eq:state_units}
111 The 1000 isn't in \fref{eq:state} above, because it is unit-dependent.
113 \subsection{Forward adjustments ($k_{fi\mathrm{adj}}$)}
115 The forward rate constant adjustment, $k_{fi\mathrm{adj}}$ takes into
116 account unsaturation ($un_f$), charge ($ch_f$), curvature ($cu_f$),
117 length ($l_f$), and complex formation ($CF1_f$), each of which are
118 modified depending on the specific specie and the vesicle into which
119 the specie is entering.
122 k_{fi\mathrm{adj}} = un_f \cdot ch_f \cdot cu_f \cdot l_f \cdot CF1_f
127 \subsubsection{Unsaturation Forward}
129 In order for a lipid to be inserted into a membrane, a void has to be
130 formed for it to fill. Voids can be generated by the combination of
131 unsaturated and saturated lipids forming herterogeneous domains. Void
132 formation is increased when the unsaturation of lipids in the vesicle
133 is widely distributed; in other words, the insertion of lipids into
134 the membrane is greater when the standard deviation of the
135 unsaturation is larger. Assuming that an increase in width of the
136 distribution linearly decreases the free energy of activation, the
137 $un_f$ parameter must follow
138 $a^{\mathrm{stdev}\left(un_\mathrm{ves}\right)}$ where $a > 1$, so a
139 convenient starting base for $a$ is $2$:
142 un_f = 2^{\mathrm{stdev}\left(un_\mathrm{ves}\right)}
143 \label{eq:unsaturation_forward}
146 The most common $\mathrm{stdev}\left(un_\mathrm{ves}\right)$ is around
147 $1.5$, which leads to a $\Delta \Delta G^\ddagger$ of
148 $\Sexpr{format(digits=3,to.kcal(2^1.5))}
149 \frac{\mathrm{kcal}}{\mathrm{mol}}$.
151 \setkeys{Gin}{width=3.2in}
152 <<fig=TRUE,echo=FALSE,results=hide,width=5,height=5>>=
153 curve(2^x,from=0,to=sd(c(0,4)),
154 main="Unsaturation Forward",
155 xlab="Standard Deviation of Unsaturation of Vesicle",
156 ylab="Unsaturation Forward Adjustment")
158 <<fig=TRUE,echo=FALSE,results=hide,width=5,height=5>>=
159 curve(to.kcal(2^x),from=0,to=sd(c(0,4)),
160 main="Unsaturation forward",
161 xlab="Standard Deviation of Unsaturation of Vesicle",
162 ylab="Unsaturation Forward (kcal/mol)")
167 \subsubsection{Charge Forward}
169 A charged lipid such as PS approaching a vesicle with an average
170 charge of the same sign will experience repulsion, whereas those with
171 different signs will experience attraction, the degree of which is
172 dependent upon the charge of the monomer and the average charge of the
173 vesicle. If either the vesicle or the monomer has no charge, there
174 should be no effect of charge upon the rate. This leads us to the
175 following equation, $a^{-\left<ch_v\right> ch_m}$, where
176 $\left<ch_v\right>$ is the average charge of the vesicle, and $ch_m$
177 is the charge of the monomer. If either $\left<ch_v\right>$ or $ch_m$
178 is 0, the adjustment parameter is 1 (no change), whereas it decreases
179 if both are positive or negative, as the product of two real numbers
180 with the same sign is always positive. A convenient base for $a$ is
181 60, resulting in the following equation:
185 ch_f = 60^{-\left<{ch}_v\right> {ch}_m}
186 \label{eq:charge_forward}
189 The most common $\left<{ch}_v\right>$ is around $-0.165$, which leads to
190 a range of $\Delta \Delta G^\ddagger$ from
191 $\Sexpr{format(digits=3,to.kcal(60^(-.165*-1)))}
192 \frac{\mathrm{kcal}}{\mathrm{mol}}$ to $0\frac{\mathrm{kcal}}{\mathrm{mol}}$.
194 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
195 x <- seq(-1,0,length.out=20)
196 y <- seq(-1,0,length.out=20)
197 grid <- expand.grid(x=x,y=y)
198 grid$z <- as.vector(60^(-outer(x,y)))
199 print(wireframe(z~x*y,grid,cuts=50,
201 scales=list(arrows=FALSE),
202 main="Charge Forward",
203 xlab=list("Average Vesicle Charge",rot=30),
204 ylab=list("Component Charge",rot=-35),
205 zlab=list("Charge Forward",rot=93)))
208 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
209 x <- seq(-1,0,length.out=20)
210 y <- seq(-1,0,length.out=20)
211 grid <- expand.grid(x=x,y=y)
212 grid$z <- as.vector(to.kcal(60^(-outer(x,y))))
213 print(wireframe(z~x*y,grid,cuts=50,
215 scales=list(arrows=FALSE),
216 main="Charge Forward (kcal/mol)",
217 xlab=list("Average Vesicle Charge",rot=30),
218 ylab=list("Component Charge",rot=-35),
219 zlab=list("Charge Forward (kcal/mol)",rot=93)))
225 \subsubsection{Curvature Forward}
227 Curvature is a measure of the intrinsic propensity of specific lipids
228 to form micelles (positive curvature), inverted micelles (negative
229 curvature), or planar sheets (zero curvature). In this formalism,
230 curvature is measured as the ratio of the size of the head to that of
231 the base, so negative curvature is bounded by $(0,1)$, zero curvature
232 is 1, and positive curvature is bounded by $(1,\infty)$. The curvature
233 can be transformed into the typical postive/negative mapping using
234 $\log$, which has the additional property of making the range of
235 positive and negative curvature equal, and distributed about 0.
237 As in the case of unsaturation, void formation is increased by the
238 presence of lipids with mismatched curvature. Thus, a larger
239 distribution of curvature in the vesicle increases the rate of lipid
240 insertion into the vesicle. However, a species with curvature $e^{-1}$
241 will cancel out a species with curvature $e$, so we have to log
242 transform (turning these into -1 and 1), then take the absolute value
243 (1 and 1), and finally measure the width of the distribution. Thus, by
244 using the log transform to make the range of the lipid curvature equal
245 between positive and negative, and taking the average to cancel out
246 exactly mismatched curvatures, we come to an equation with the shape
247 $a^{\left<\log cu_\mathrm{vesicle}\right>}$. A convenient base for $a$
252 % cu_f = 10^{\mathrm{stdev}\left|\log cu_\mathrm{vesicle}\right|}
253 cu_f = 10^{\left|\left<\log cu_\mathrm{vesicle} \right>\right|\mathrm{stdev} \left|\log cu_\mathrm{vesicle}\right|}
254 \label{eq:curvature_forward}
257 The most common $\left|\left<\log {cu}_v\right>\right|$ is around
258 $0.013$, which with the most common $\mathrm{stdev} \log
259 cu_\mathrm{vesicle}$ of $0.213$ leads to a $\Delta \Delta G^\ddagger$
260 of $\Sexpr{format(digits=3,to.kcal(10^(0.13*0.213)))}
261 \frac{\mathrm{kcal}}{\mathrm{mol}}$. This is a consequence of the
262 relatively matched curvatures in our environment.
264 % 1.5 to 0.75 3 to 0.33
265 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
266 grid <- expand.grid(x=seq(0,max(c(sd(abs(log(c(1,3)))),
267 sd(abs(log(c(1,0.33)))),sd(abs(log(c(0.33,3)))))),length.out=20),
268 y=seq(0,max(c(mean(log(c(1,3)),
269 mean(log(c(1,0.33))),
270 mean(log(c(0.33,3)))))),length.out=20))
271 grid$z <- 10^(grid$x*grid$y)
272 print(wireframe(z~x*y,grid,cuts=50,
274 scales=list(arrows=FALSE),
275 xlab=list("Vesicle stdev log curvature",rot=30),
276 ylab=list("Vesicle average log curvature",rot=-35),
277 zlab=list("Vesicle Curvature Forward",rot=93)))
280 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
281 grid <- expand.grid(x=seq(0,max(c(sd(abs(log(c(1,3)))),
282 sd(abs(log(c(1,0.33)))),sd(abs(log(c(0.33,3)))))),length.out=20),
283 y=seq(0,max(c(mean(log(c(1,3)),
284 mean(log(c(1,0.33))),
285 mean(log(c(0.33,3)))))),length.out=20))
286 grid$z <- to.kcal(10^(grid$x*grid$y))
287 print(wireframe(z~x*y,grid,cuts=50,
289 scales=list(arrows=FALSE),
290 xlab=list("Vesicle stdev log curvature",rot=30),
291 ylab=list("Vesicle average log curvature",rot=-35),
292 zlab=list("Vesicle Curvature Forward (kcal/mol)",rot=93)))
297 \subsubsection{Length Forward}
299 As in the case of unsaturation, void formation is easier when vesicles
300 are made up of components of widely different lengths. Thus, when the
301 width of the distribution of lengths is larger, the forward rate
302 should be greater as well, leading us to an equation of the form
303 $x^{\mathrm{stdev} l_\mathrm{ves}}$, where $\mathrm{stdev}
304 l_\mathrm{ves}$ is the standard deviation of the length of the
305 components of the vesicle, which has a maximum possible value of 8 and
306 a minimum of 0 in this set of experiments. A convenient base for $x$
310 l_f = 2^{\mathrm{stdev} l_\mathrm{ves}}
311 \label{eq:length_forward}
314 The most common $\mathrm{stdev} l_\mathrm{ves}$ is around $3.4$, which leads to
315 a range of $\Delta \Delta G^\ddagger$ of
316 $\Sexpr{format(digits=3,to.kcal(2^(3.4)))}
317 \frac{\mathrm{kcal}}{\mathrm{mol}}$.
320 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=5>>=
321 curve(2^x,from=0,to=sd(c(12,24)),
322 main="Length forward",
323 xlab="Standard Deviation of Length of Vesicle",
324 ylab="Length Forward Adjustment")
326 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=5>>=
327 curve(to.kcal(2^x),from=0,to=sd(c(12,24)),
328 main="Length forward",
329 xlab="Standard Deviation of Length of Vesicle",
330 ylab="Length Forward Adjustment (kcal/mol)")
334 \subsubsection{Complex Formation}
335 There is no contribution of complex formation to the forward reaction
336 rate in the current formalism.
340 \label{eq:complex_formation_forward}
343 \subsection{Backward adjustments ($k_{bi\mathrm{adj}}$)}
345 Just as the forward rate constant adjustment $k_{fi\mathrm{adj}}$
346 does, the backwards rate constant adjustment $k_{bi\mathrm{adj}}$
347 takes into account unsaturation ($un_b$), charge ($ch_b$), curvature
348 ($cu_b$), length ($l_b$), and complex formation ($CF1_b$), each of
349 which are modified depending on the specific specie and the vesicle
350 into which the specie is entering:
354 k_{bi\mathrm{adj}} = un_b \cdot ch_b \cdot cu_b \cdot l_b \cdot CF1_b
358 \subsubsection{Unsaturation Backward}
360 Unsaturation also influences the ability of a lipid molecule to leave
361 a membrane. If a molecule has an unsaturation level which is different
362 from the surrounding membrane, it will be more likely to leave the
363 membrane. The more different the unsaturation level is, the greater
364 the propensity for the lipid molecule to leave. However, a vesicle
365 with some unsaturation is more favorable for lipids with more
366 unsaturation than the equivalent amount of less unsatuturation, so the
367 difference in energy between unsaturation is not linear. Therefore, an
368 equation with the shape
369 $x^{\left| y^{-\left< un_\mathrm{ves}\right> }-y^{-un_\mathrm{monomer}} \right| }$
370 where $\left<un_\mathrm{ves}\right>$ is the average unsaturation of
371 the vesicle, and $un_\mathrm{monomer}$ is the average unsaturation. In
372 this equation, as the average unsaturation of the vesicle is larger,
375 un_b = 10^{\left(2^{- \left< un_\mathrm{ves} \right> }
376 -2^{-un_\mathrm{monomer}}\right)^2}
377 \label{eq:unsaturation_backward}
380 The most common $\left<un_\mathrm{ves}\right>$ is around $1.7$, which leads to
381 a range of $\Delta \Delta G^\ddagger$ from
382 $\Sexpr{format(digits=3,to.kcal(10^((2^-1.7-2^-0)^2)))}
383 \frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with 0 unsaturation
385 $\Sexpr{format(digits=3,to.kcal(10^((2^-1.7-2^-4)^2)))}\frac{\mathrm{kcal}}{\mathrm{mol}}$
386 for monomers with 4 unsaturations.
389 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
390 grid <- expand.grid(x=seq(0,4,length.out=20),
391 y=seq(0,4,length.out=20))
392 grid$z <- 10^((2^-grid$x-2^-grid$y)^2)
393 print(wireframe(z~x*y,grid,cuts=50,
395 scales=list(arrows=FALSE),
396 xlab=list("Average Vesicle Unsaturation",rot=30),
397 ylab=list("Monomer Unsaturation",rot=-35),
398 zlab=list("Unsaturation Backward",rot=93)))
401 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
402 grid <- expand.grid(x=seq(0,4,length.out=20),
403 y=seq(0,4,length.out=20))
404 grid$z <- to.kcal(10^((2^-grid$x-2^-grid$y)^2))
405 print(wireframe(z~x*y,grid,cuts=50,
407 scales=list(arrows=FALSE),
408 xlab=list("Average Vesicle Unsaturation",rot=30),
409 ylab=list("Monomer Unsaturation",rot=-35),
410 zlab=list("Unsaturation Backward (kcal/mol)",rot=93)))
414 \subsubsection{Unsaturation Backward II}
416 Unsaturation also influences the ability of a lipid molecule to leave
417 a membrane. If a molecule has an unsaturation level which is different
418 from the surrounding membrane, it will be more likely to leave the
419 membrane. The more different the unsaturation level is, the greater
420 the propensity for the lipid molecule to leave. However, a vesicle
421 with some unsaturation is more favorable for lipids with more
422 unsaturation than the equivalent amount of less unsatuturation, so the
423 difference in energy between unsaturation is not linear. Therefore, an
424 equation with the shape
425 $x^{\left| y^{-\left< un_\mathrm{ves}\right> }-y^{-un_\mathrm{monomer}} \right| }$
426 where $\left<un_\mathrm{ves}\right>$ is the average unsaturation of
427 the vesicle, and $un_\mathrm{monomer}$ is the average unsaturation. In
428 this equation, as the average unsaturation of the vesicle is larger,
431 un_b = 7^{1-\left(20\left(2^{-\left<un_\mathrm{vesicle} \right>} - 2^{-un_\mathrm{monomer}} \right)^2+1\right)^{-1}}
432 \label{eq:unsaturation_backward}
435 The most common $\left<un_\mathrm{ves}\right>$ is around $1.7$, which leads to
436 a range of $\Delta \Delta G^\ddagger$ from
437 $\Sexpr{format(digits=3,to.kcal(7^(1-1/(5*(2^-1.7-2^-0)^2+1))))}
438 \frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with 0 unsaturation
440 $\Sexpr{format(digits=3,to.kcal(7^(1-1/(5*(2^-1.7-2^-4)^2+1))))}\frac{\mathrm{kcal}}{\mathrm{mol}}$
441 for monomers with 4 unsaturations.
444 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
445 grid <- expand.grid(x=seq(0,4,length.out=20),
446 y=seq(0,4,length.out=20))
447 grid$z <- (7^(1-1/(5*(2^-grid$x-2^-grid$y)^2+1)))
448 print(wireframe(z~x*y,grid,cuts=50,
450 scales=list(arrows=FALSE),
451 xlab=list("Average Vesicle Unsaturation",rot=30),
452 ylab=list("Monomer Unsaturation",rot=-35),
453 zlab=list("Unsaturation Backward",rot=93)))
456 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
457 grid <- expand.grid(x=seq(0,4,length.out=20),
458 y=seq(0,4,length.out=20))
459 grid$z <- to.kcal((7^(1-1/(5*(2^-grid$x-2^-grid$y)^2+1))))
460 print(wireframe(z~x*y,grid,cuts=50,
462 scales=list(arrows=FALSE),
463 xlab=list("Average Vesicle Unsaturation",rot=30),
464 ylab=list("Monomer Unsaturation",rot=-35),
465 zlab=list("Unsaturation Backward (kcal/mol)",rot=93)))
472 \subsubsection{Charge Backwards}
473 As in the case of monomers entering a vesicle, monomers leaving a
474 vesicle leave faster if their charge has the same sign as the average
475 charge vesicle. An equation of the form $ch_b = a^{\left<ch_v\right>
476 ch_m}$ is then appropriate, and using a base of $a=20$ yields:
479 ch_b = 20^{\left<{ch}_v\right> {ch}_m}
480 \label{eq:charge_backwards}
483 The most common $\left<ch_v\right>$ is around $-0.164$, which leads to
484 a range of $\Delta \Delta G^\ddagger$ from
485 $\Sexpr{format(digits=3,to.kcal(20^(-.164*-1)))}
486 \frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with charge $-1$ to
487 $0\frac{\mathrm{kcal}}{\mathrm{mol}}$
488 for monomers with charge $0$.
491 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
492 x <- seq(-1,0,length.out=20)
493 y <- seq(-1,0,length.out=20)
494 grid <- expand.grid(x=x,y=y)
495 grid$z <- as.vector(20^(outer(x,y)))
496 print(wireframe(z~x*y,grid,cuts=50,
498 scales=list(arrows=FALSE),
499 xlab=list("Average Vesicle Charge",rot=30),
500 ylab=list("Component Charge",rot=-35),
501 zlab=list("Charge Backwards",rot=93)))
504 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
505 x <- seq(-1,0,length.out=20)
506 y <- seq(-1,0,length.out=20)
507 grid <- expand.grid(x=x,y=y)
508 grid$z <- to.kcal(as.vector(20^(outer(x,y))))
509 print(wireframe(z~x*y,grid,cuts=50,
511 scales=list(arrows=FALSE),
512 xlab=list("Average Vesicle Charge",rot=30),
513 ylab=list("Component Charge",rot=-35),
514 zlab=list("Charge Backwards (kcal/mol)",rot=93)))
519 \subsubsection{Curvature Backwards}
521 The less a monomer's intrinsic curvature matches the average curvature
522 of the vesicle in which it is in, the greater its rate of efflux. If
523 the difference is 0, $cu_f$ needs to be one. To map negative and
524 positive curvature to the same range, we also need take the logarithm.
525 Increasing mismatches in curvature increase the rate of efflux, but
526 asymptotically. \textcolor{red}{It is this property which the
527 unsaturation backwards equation does \emph{not} satisfy, which I
528 think it should.} An equation which satisfies this critera has the
529 form $cu_f = a^{1-\left(b\left( \left< \log cu_\mathrm{vesicle} \right>
530 -\log cu_\mathrm{monomer}\right)^2+1\right)^{-1}}$. An
531 alternative form would use the aboslute value of the difference,
532 however, this yields a cusp and sharp increase about the curvature
533 equilibrium, which is decidedly non-elegant. We have chosen bases of
537 cu_b = 7^{1-\left(20\left(\left< \log cu_\mathrm{vesicle} \right> -\log cu_\mathrm{monomer} \right)^2+1\right)^{-1}}
538 \label{eq:curvature_backwards}
541 The most common $\left<\log cu_\mathrm{ves}\right>$ is around $-0.013$, which leads to
542 a range of $\Delta \Delta G^\ddagger$ from
543 $\Sexpr{format(digits=3,to.kcal(7^(1-1/(20*(-0.013-log(0.8))^2+1))))}
544 \frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with curvature 0.8
546 $\Sexpr{format(digits=3,to.kcal(7^(1-1/(20*(-0.013-log(1.3))^2+1))))}\frac{\mathrm{kcal}}{\mathrm{mol}}$
547 for monomers with curvature 1.3 to $0\frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with curvature near 1.
550 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
551 grid <- expand.grid(x=seq(0.8,1.33,length.out=20),
552 y=seq(0.8,1.33,length.out=20))
553 grid$z <- 7^(1-1/(20*(log(grid$x)-log(grid$y))^2+1))
554 print(wireframe(z~x*y,grid,cuts=50,
556 scales=list(arrows=FALSE),
557 xlab=list("Vesicle Curvature",rot=30),
558 ylab=list("Monomer Curvature",rot=-35),
559 zlab=list("Curvature Backward",rot=93)))
562 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
563 grid <- expand.grid(x=seq(0.8,1.33,length.out=20),
564 y=seq(0.8,1.33,length.out=20))
565 grid$z <- to.kcal(7^(1-1/(20*(log(grid$x)-log(grid$y))^2+1)))
566 print(wireframe(z~x*y,grid,cuts=50,
568 scales=list(arrows=FALSE),
569 xlab=list("Vesicle Curvature",rot=30),
570 ylab=list("Monomer Curvature",rot=-35),
571 zlab=list("Curvature Backward (kcal/mol)",rot=93)))
576 \subsubsection{Length Backwards}
578 In a model membrane, the dissociation constant increases by a factor
579 of approximately 3.2 per carbon decrease in acyl chain length (Nichols
580 1985). Unfortunatly, the experimental data known to us only measures
581 chain length less than or equal to the bulk lipid, and does not exceed
582 it, and is only known for one bulk lipid species (DOPC). We assume
583 then, that the increase is in relationship to the average vesicle, and
584 that lipids with larger acyl chain length will also show an increase
585 in their dissociation constant.
588 l_b = 3.2^{\left|\left<l_\mathrm{ves}\right>-l_\mathrm{monomer}\right|}
589 \label{eq:length_backward}
592 The most common $\left<\log l_\mathrm{ves}\right>$ is around $17.75$, which leads to
593 a range of $\Delta \Delta G^\ddagger$ from
594 $\Sexpr{format(digits=3,to.kcal(3.2^abs(12-17.75)))}
595 \frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with length 12
597 $\Sexpr{format(digits=3,to.kcal(3.2^abs(24-17.75)))}\frac{\mathrm{kcal}}{\mathrm{mol}}$
598 for monomers with length 24 to $0\frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with curvature near 18.
601 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
602 grid <- expand.grid(x=seq(12,24,length.out=20),
603 y=seq(12,24,length.out=20))
604 grid$z <- 3.2^(abs(grid$x-grid$y))
605 print(wireframe(z~x*y,grid,cuts=50,
607 scales=list(arrows=FALSE),
608 xlab=list("Average Vesicle Length",rot=30),
609 ylab=list("Monomer Length",rot=-35),
610 zlab=list("Length Backward",rot=93)))
613 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
614 grid <- expand.grid(x=seq(12,24,length.out=20),
615 y=seq(12,24,length.out=20))
616 grid$z <- to.kcal(3.2^(abs(grid$x-grid$y)))
617 print(wireframe(z~x*y,grid,cuts=50,
619 scales=list(arrows=FALSE),
620 xlab=list("Average Vesicle Length",rot=30),
621 ylab=list("Monomer Length",rot=-35),
622 zlab=list("Length Backward (kcal/mol)",rot=93)))
628 \subsubsection{Complex Formation Backward}
633 CF1_b=1.5^{\left<CF1_\mathrm{ves}\right> CF1_\mathrm{monomer}-\left|\left<CF1_\mathrm{ves}\right> CF1_\mathrm{monomer}\right|}
634 \label{eq:complex_formation_backward}
637 The most common $\left<CF1_\mathrm{ves}\right>$ is around $0.925$, which leads to
638 a range of $\Delta \Delta G^\ddagger$ from
639 $\Sexpr{format(digits=3,to.kcal(1.5^(0.925*-1-abs(0.925*-1))))}
640 \frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with complex formation $-1$
642 $\Sexpr{format(digits=3,to.kcal(1.5^(0.925*2-abs(0.925*2))))}\frac{\mathrm{kcal}}{\mathrm{mol}}$
643 for monomers with length $2$ to $0\frac{\mathrm{kcal}}{\mathrm{mol}}$ for monomers with complex formation $0$.
646 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
647 grid <- expand.grid(x=seq(-1,3,length.out=20),
648 y=seq(-1,3,length.out=20))
649 grid$z <- 1.5^(grid$x*grid$y-abs(grid$x*grid$y))
650 print(wireframe(z~x*y,grid,cuts=50,
652 scales=list(arrows=FALSE),
653 xlab=list("Vesicle Complex Formation",rot=30),
654 ylab=list("Monomer Complex Formation",rot=-35),
655 zlab=list("Complex Formation Backward",rot=93)))
658 <<fig=TRUE,echo=FALSE,results=hide,width=7,height=7>>=
659 grid <- expand.grid(x=seq(-1,3,length.out=20),
660 y=seq(-1,3,length.out=20))
661 grid$z <- to.kcal(1.5^(grid$x*grid$y-abs(grid$x*grid$y)))
662 print(wireframe(z~x*y,grid,cuts=50,
664 scales=list(arrows=FALSE),
665 xlab=list("Vesicle Complex Formation",rot=30),
666 ylab=list("Monomer Complex Formation",rot=-35),
667 zlab=list("Complex Formation Backward (kcal/mol)",rot=93)))
675 % \bibliographystyle{plainnat}
676 % \bibliography{references.bib}