IFCC method for alanine aminotransferase

171F

Clinica Chimica Ada,

INTERNATIONAL

105 (1980)

171F-172F

FEDERATION

OF CLINICAL CHEMISTRY

IFCC METHOD FOR ALANINE AMINOTRANSFERASE Stage 2, Draft 1, 1979-11-19

Appendix C A comparison of the catalytic activities calculated the two substrates for alanine aminotransferase

for various combinations

of

Appendix A describes how the pair of substrate concentrations selected will yield 0,91 of the theoretical, maximal velocity obtainable under the defined conditions of temperature, buffer, pH, co-factors etc. It has been demonstrated also that a constant fraction of the maximal velocity may be obtained for other combinations of substrate concentrations. Such pairs of substrates lie on a

TABLE I NOMOGRAM SHOWING THE CONCENTRATION OF L-ALANINE [SI J AS A FUNCTION OF Z-OXOGLUTARATE [SzJ, AND THE FRACTIONAL, MAXIMAL VELOCITY [vi/V] OF ALANINE AMINOTRANSFERASE. *

0.81 5 6 1 8 9 10 11 12 13 14 15 16 11 18 19 20

0,88

0.89

0.90

0.91

0.92

0.93

0.94

0.95

-

-

-

-

-

-

-

-

-

646 438 354 308 210 260 245 235 226 220 214 210 206 203

590 446 315 333 306 286 212 260 251 244 238 233 229

598 411 411 310 341 321 305 293 283 215 268 263

650 533 465 421 390 361 349 335 324 315 301

151 622 545 493 451 430 408 392 318 361

166 667 602 555 520 492 411 453

716 109 658 620 589

898 834

-

200

226

258

300

351

438

564

184

(1268)

* The values refer to human seem containing alanine aminotransferase from patients with liver diseases. The equation from which the nomogram was constructed and the values of the kinetic constants are described in Appendix A (P. 163F and Table II). If no concentration of [SIJ is given, the values cakulated are above the limit of solubility of SI.

172F TABLE II NOMOGRAM SHOWING THE CONCENTRATION OF L-ALANINE [SII AS A FUNCTION OF 2-0X0GLUTARATE [Szl. AND THE FRACTIONAL, MAXIMAL VELOCITY [Vi/VI OF ALANINE AMINOTRANSFERASE. *

0.89

0.88

5 6 7 8 9 10 11 12 13 14 15

971 598 466 398 356 329 309 294 283 274

842 601 492 430 390 363 342 327 315

-

-

837 639 538 477 436 407 385 368

905 715 610 545 500 467 442

839 719 642 589 550

891 791 721

16 17

267 261

305 297

355 344

423 407

520 496

670 630

18 19 20

256 251 248

290 285 280

335 328 321

394 384 375

477 461 448

600 575 554

0.90

0.91

0,92

0.87

-

0.93

-

-

-

-

0.94

0.95 -

-

-

-

-

-

934 858

-

-

802 757 721

(1195) (1098) (1023)

-

-

* Thg values refer to human serum containing alanine aminotransferase from patients with heart diseases. The equation from which the nomogram was constructed and the values of the kinetic constants are described in Appendix A (p. 163F and Table II). If no concentration of [Sll is given. the values cakulated are above the limit of solubility of SI .

parabola, conf. Fig. 8, Appendix A. For the purpose of comparison, v/V has been calculated from the rate equation (p. 164F of Appendix A) and using the numerical values of the kinetic constants described in Table I of Appendix A for different substrate pair combinations. It is thus possible from the two tables to find pairs of substrates that will yield the identical initial velocity or alternatively to find out the change in Vi that wilI result from the increase or decrease in one or both substrate concentrations, It should be stressed that the values of the tables are valid for the system under consideration, i.e. alanine aminotransferase in human serum obtained from patients with liver (Table I) and heart (Table II) diseases. It is valid also only for measurements performed under conditions of this method except for the variation in substrate concentrations.