The study adapts Anfinsen’s Nobel-winning experiment of protein folding into
biology investigation for secondary and college students. This experiment is
significant for secondary and college science learning not only for its
associations with some core concepts in biology, but also for its rich nature of
science and science practices. The lab procedure of the original experiment was
modified to be accessible to secondary biology teachers and students. A detailed
lab manual and task sheet are available.
Key Words: biology investigation; protein folding; Anfinsen.
The study will try to adapt Anfinsen’s Nobel-winning experiment
about protein folding (Anfinsen & Haber, 1961) into biology investigation for secondary and college students. This experiment is significant for biology learning not only for its associations with some core
concepts in biology—genes, proteins, and traits (LS1 and LS3 in
NGSS, 2013)—but also for its rich nature of science and science practices. The experiment, however, is not commonly done in secondary
schools because the expertise and equipment required are beyond secondary levels, and no appropriate resources are available. This study
will try to modify the experiment to make it accessible to most biology
teachers and students.
Christian Boehmer Anfinsen received the Nobel Prize for
Chemistry in 1972 for his investigation into how a protein folds
into its native shape. He and his collaborators discovered that ribo-
nuclease (RNase) could spontaneously refold back into its active
shape after being fully unfolded by denaturants (Figure 1). This
shows that all the information required for a polypeptide chain to
fold into its active shape must reside in the amino acid sequence
rather than be imparted from anything else during protein synthe-
sis, such as DNA, RNA, ribosome, and enzymes. The correct refold-
ing, however, only took place in an environment with specific pH
and temperature. When urea is present to disrupt the hydrophobic
environment, the unfolded proteins will only refold randomly into
“scrambled” proteins that have no catalytic activity (Figure 1).
Anfinsen (1973) further proposed a thermodynamic hypothesis to
account for the protein folding: “the three-dimensional structure
of a native protein in its normal physiological milieu (solvent,
pH, ionic strength, presence of other components such as metal
ions or prosthetic groups, temperature, etc.) is the one in which
the Gibbs free energy of the whole system is lowest; that is, that
the native conformation is determined by the totality of interatomic
interactions and hence by the amino acid sequence, in a given envi-
ronment” (p. 56). Anfinsen and others’ work had established an
important principle in biology that a gene determines the amino
acid sequence, and the sequence in turn determines the active
shape, and this shape ultimately determines the biological functions
(Kresge et al., 2006) (Figure 2).
The protein folding investigation can help tackle some common
misconceptions associated with enzymes, proteins, and inheritance.
In a study, 61 percent of secondary students considered genes as
traits, 21 percent considereed genes as proteins and amino acids,
while only 16 percent correctly stated genes are sequences of nucleotides (Marbach-Ad, 2001; AAAS project 2061, n.d.). Only 25 percent
of students correctly answered that the information for making proteins comes from DNA, while 50 percent thought it is from amino
acid and 25 percent from enzymes (AAAS project 2061, n.d.). There
are 50% of students thought that DNA is made of proteins or amino
acid (Marbach-Ad, 2001). This protein folding investigation can help
clarify some of these misconceptions by engaging students in thinking
about how information flows from DNA to proteins to traits.
The following concepts are the core ideas in the Next Generation Science Standards (NGSS, 2013):
• Genes are regions in the DNA that contain the instructions that
code for the formation of proteins, which carry out most of the
work of cells (LS1, grade 12).
The American Biology Teacher, Vol. 80, No 5, pages. 379–384, ISSN 0002-7685, electronic ISSN 1938-4211. © 2018 National Association of Biology Teachers. All rights
reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Reprints and Permissions web page,
www.ucpress.edu/journals.php?p=reprints. DOI: https://doi.org/10.1525/abt.2018.80.5.379.
THE AMERICAN BIOLOGY TEACHER PROTEIN FOLDING
An Adaptation of Anfinsen’s
Protein-Folding Experiment for
• KWOK-CHI LAU, ANTHONY HIU-FUNG LO,