María Luz Cárdenas

Cárdenas's doctoral research led to a major discovery, that rat-liver hexokinase D (often called “glucokinase”) was a monomeric enzyme^[6] that displayed positive cooperativity,^[7] later confirmed by others.^[8] Although kinetic models of cooperativity had been proposed (for example by Ferdinand^[9] and by Rabin^[10]) these were not widely believed to have practical importance, and cooperativity was usually assumed to require binding equilibrium and interactions between multiple binding sites. Hexokinase D was thus the first enzyme for which the cooperativity could not be explained in terms of the best known models.^[11][12] Cárdenas and co-workers suggested that the cooperativity could be explained by a slow-transition model.^[13]

The name “glucokinase” for hexokinase D is now virtually universal in the literature, and there is little likelihood of changing that. However, it is important to realize that it is a misleading name, because it implies that hexokinase D is more specific for glucose than the other mammalian hexokinases, but that is not the case, as it accepts fructose as a good substrate.^[14]

Although the monomeric cooperativity exhibited by hexokinase D proved to be rare, it was not the only example.^[15]

Cárdenas's book “Glucokinase”: Its Regulation and Role in Liver Metabolism collects a large amount of information about the enzyme, not only about its kinetics and cooperativity, but its physiological importance in regulating glucose uptake by the liver, and genetic aspects.^[4] Her work on hexokinase D inevitably led to study of the other mammalian hexokinase isoenzymes and their evolution, as set out in her review.^[16]

In the last 20 years of her career, Cárdenas's interest turned to the nature of life,^[17] self-organization,^[18] and LUCA (the last universal common ancestor).^[19]

In 1993 Cárdenas was appointed to the honorary chair "Hermann Niemeyer F." at the Faculty of Sciences of the University de Chile.^[1] In 2002 she was elected corresponding member of the Chilean Academy of Sciences.^[20] In 2016 she was awarded the Tito Ureta Prize of the Chilean Society of Biochemistry and Molecular Biology.^[21] In 2023 she was elected Honorary Member of the Spanish Society of Biochemistry and Molecular Biology.^[22] In 2024 the French Society of Biochemistry and Molecular Biology nominated her as one of 36 women scientists celebrated by FEBS,^[1] recognizing her creation as a thematic group of the Society the Association pour les Femmes en Sciences et Ingénierie as a way of contributing to the visibility of women scientists,^[23]